Prokaryotes

Experientia, 1979 May 15, 35(5), 578 - 9
Polyamines as activators of AMP nucleosidase from Azotobacter vinelandii; Yoshino M et al.; Polyamines at physiological concentrations activate AMP nucleosidase from Azotobacter vinelandii . Biological significance of the activation is discussed in relation to the control of adenylate energy charge and the purine nucleotide synthesis in prokaryotes.

Mol Cell Biochem, 1979 May 6, 25(1), 43 - 6
Myo-inositol-1-phosphate synthase from streptomyces griseus (studies on the biosynthesis of cyclitols, XXXVIII); Pittner F et al.; It could be shown that Streptomyces griseus, the microorganism producing the antibiotic streptomycin and also mutant strains of this species that cannot synthesize streptomycin, possess myo-inositol-1-phosphate synthase (EC 5.5.1.4), the enzyme cyclizing D-glucose 6-phosphate . The enzyme isolated from that organism is extremely instable, its molecular weight is approximately 260,000, and it requires a divalent metal ion for its activity . This is the first instance that an enzyme of this specificity has been found in a prokaryotic organism.

J Protozool, 1979 May, 26(2), 290 - 4
RNA synthesis in isolated nuclei of the dinoflagellate Crypthecodinium cohnii; Rizzo PJ; Atypical eukaryotic RNA polymerase activity was demonstrated in nuclei of Crypthecodinium cohnii, a eukaryote devoid of histones . Nuclei were isolated from growing cultures of this dinoflagellate and assayed for endogenous RNA polymerase (EC 2.7.7.6) activity . There was a biphasic response to Mg2+ with optima at approximately 0.01 and 0.02 M MgCl2, but in contrast to other eukaryotic RNA polymerases, this enzyme activity was inhibited by low MnCl2 concentrations . In the presence of 0.01 M MgCL2 the optimum (NH4)2SO4 concentration was 0.025 M, a concentration at which the nuclei were lysed . Incorporation of {3H}UMP into RNA was inhibited by actinomycin D and dependent on the presence of undergraded DNA, and the reaction product was sensitive to ribonuclease and KOH digestion . Omission of one or more ribonucleoside triphosphates greatly reduced the incorporation . Only a slight enhancement of RNA polymerase activity resulted from the addition of various amounts of native and denatured calf thymus DNA . Spermine caused a marked inhibition while spermidine had little effect on RNA synthesis in the nuclei . Under the optimum conditions described in the present paper the nuclei incorporated approximately 3 pmoles of {3H}UMP/microgram DNA at 25 C for 15 min, and approximately 80% of this activity was inhibited by the eukaryotic RNA polymerase II inhibitor, alpha-amanitin (20 micrograms/ml) . A unique situation therefore exists in C . cohnii nuclei, in which absence of histones (a prokaryotic trait) is combined with alpha-amanitin-sensitive RNA polymerase activity (a eukaryotic trait).

Z Naturforsch {C}, 1979 May-Jun, 34C(5-6), 374 - 80
Cyanide insensitive iron superoxide dismutase in Euglena gracilis . Comparison of the reliabilities of different test systems for superoxide dismutases; Lengfelder E et al.; Two proteins (P1 and P2, with weights of 57,500 and 27,500 respectively) were isolated from Euglena gracilis . Both proteins show cyanide-insensitive superoxide dismutase activity in the "classical" superoxide dismutase assay, using xanthine-xanthine oxidase as O2.- generator . If O2.- is generated chemically (autoxidation of reduced anthraquinone), photochemically (illuminated riboflavine) or pulse radiolytically, only protein P1 but not P2 shows SOD activity . Protein P1 contains 1 g atom (determined: 0.82) iron (no Mn or Cu) per mole protein and may thus be defined as iron-superoxide dismutase . Protein P2, showing the spectral properties of a flavoprotein, exhibits the activities of ferredoxin-NADP-oxidoreductase and "diaphorase" . The cyanide-insensitive SOD-activity of this Diaphorase" in the xanthine oxidase-assay for superoxide dismutase makes this classical and commonly used test unreliable for assay cyanide insensitive SOD activities . The existence of the "prokaryote-type" of superoxide dismutase (Fe-SOD) in Euglena gracilis is exceptional for an eukaryotic, autotrophically grown organisms.

Biochim Biophys Acta, 1979 Apr 25, 577(2), 400 - 9
Comparative study between prokaryotes and eukaryotes by chemical iodination of ribosomal proteins; Bernabeu C et al.; Escherichia coli and Saccharomyces cerevisiae ribosomal proteins were chemically iodinated with 125I by chloramine T under conditions in which the proteins were denatured . The labelled proteins were subsequently separated by two-dimensional gel electrophoresis with an excess of untreated ribosomal proteins from the same species . The iodination did not change the electrophoretic mobility of the proteins as shown by the pattern of spots in the stained gel slabs and their autoradiography . The 125I radioactivity incorporated in the proteins was estimated by cutting out the gel spots from the two-dimensional electrophoresis gel slabs . The highest content of 125I was found in the ribosomal proteins L2, L11, L13, L20/S12, S4 and S9 from E . coli, and L2/L3, L4/L6/S7, L5, L19/L20, L22/S17, L29/S27, L35/L37 and S14/S15 from S . cerevisiae . Comparisons between the electrophoretic patterns of E . coli and S . cerevisiae ribosomal proteins were carried out by coelectrophoresis of labelled and unlabelled proteins from both species . E . coli ribosomal proteins L5, L11, L20, S2, S3 and S15/S16 were found to overlap with L15, L11/L16, L36/L37, S3, S10 and S33 from S . cerevisiae, respectively . Similar coelectrophoresis of E . coli 125I-labelled proteins with unlabelled rat liver and wheat germ ribosomal proteins showed the former to overlap with proteins L1, L11, L14, L16, L19, L20 and the latter with L2, L5, L6, L15, L17 from E . coli.

Proc R Soc Lond B Biol Sci, 1979 Apr 11, 204(1155), 267 - 86
Symbionticism revisited: a discussion of the evolutionary impact of intracellular symbioses; Taylor FJ; Wallin (1927) first published the notion that the fusion of bacteria with host cells was the principal source of genetic novelty for speciation . He suggested that mitochondria are transitional elements in this process . While the significance that he attributed to symbiosis now seem excessive, he was one of the first authors to be aware of the evolutionary potential of symbiotic events and his view of mitochondria may not seem strange to many cell biologist today . The most significant evolutionary development which has been attributed to intracellular symbiosis is the origin of eukaryotic cellular organization . The current status of the 'serial endosymbiosis hypothesis' is briefly review . The case for the symbiotic origin of the chloroplast, based principally on 16 S RNA oligonucleotide cataloguing, is very strong . Mitochondrial origins are more obscure but also appear to be symbiotic due to recent 18 S cataloguing from wheat embryos . The probablility of the multiple origin of some eukaryotic organelles is also examined, the processes in question being the acquisition of distinct stocks of chloroplasts from disparate photosynthetic prokaryotes and the secondary donation of organelles from degenerate eukaryotic endosymbionts to their hosts, with specific reference to the dinoflagellates Peridinium balticum, Kryptoperidinium foliaceum and the ciliate Mesodinium rubrum . It is concluded that the evolutionary potential of intracellular symbiosis ('cytobiosis': a term introduced in this paper) is great, with the best established influence being on the origin of eukaryotic chloroplasts . Together with the potential effects of viral vectors, symbiosis serves as a supplementary speciation mechanism capable of producing directed evolutionary changes . It is likely that these processes will explain some of the apparent anomalies in evolutionary rates and direction which are not readily explicable by the conventional synthetic theory of evolution.

J Parasitol, 1979 Apr, 65(2), 201 - 16
Lipids of Leishmania promastigotes; Beach DH et al.; A chromatographic analysis of lipids of cultured promastigotes of Leishmania donovani, L . braziliensis, L . mexicana, L . tropica, L . enriettii, L . hertigi, L . adleri, and L . tarentolae showed that total lipids were 2--15% of dry wt, and neutral and polar lipids were 14--55% and 45--86% of total lipids . Major lipid classes were as follows: sterol ester, triacylglycerol, sterol, diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol, phosphatidylcholine . Predominant fatty acids were 18:2 (n - 6) greater than 18:3 (n - 3) greater than 18:1 (n - 9) greater than 18:0 greater than 22:6 (n - 3) greater than 22:5 (n - 6) greater than 16:0 greater than 14:0 greater than 18:4 (n - 3) greater than 20:3 (n - 3) . Some remarkable distributions of fatty acids among the phospholipid fractions were observed, as follows: diphosphatidylglycerol 18--33% 22:6 (n - 3); phosphatidylinositol 31--68% 18:1 (n - 9); phosphatidylcholine 13--41% 18:3 (n - 3) . Alk-l-enyldiacyl glycerols, and alk-l-enylacyl and alkylacyl forms of phosphatidylethanolamine and of phosphatidylinositol were found, and their glyceryl ethers and fatty adehydes analyzed . Notable in the phosphatidylethanolamine of some leishmanias was a cyclopropane fatty acid (4--11%), identified as cis-9,10-methylene octadecanoic acid by chromatographic, and by mass and proton resonance spectrometric analyses . The comparative biochemistry of the cyclopropane fatty acid, characteristic of many prokaryotes, and of alpha-linolenic acid, characteristic of photosynthetic plants, are commented upon.

Nucleic Acids Res, 1979 Apr, 6(4), 1269 - 86
The use of rifampicin to evaluate tRNA transcriptional organization in Escherichia coli; Ludi GA et al.; The antibiotic rifampicin, which in prokaryotes inhibits the initiation of RNA synthesis but not the completion of nascent strands, was used to explore tRNA gene transcriptional organization in Escherichia coli . Cultures were grown in {32P} orthophosphate to constant specific radioactivity and labeled with {3H} uridine in the presence of rifampicin . Numerous tRNA species then were isolated by polyacrylamide gel electrophoresis and their 3H/32P ratios determined; these ratios, following correction for the base compositions of the tRNAs, should reflect the distances of the corresponding tRNA genes from their promoters . Individual tRNA species were identified, where possible, by oligonucleotide fingerprint analysis . Observed isotopic ratios were correlated with promoter-gene distances, measured in nucleotides, using the nucleotide sequence of the 16S ribosomal RNA gene as a reference . The protocols developed should be applicable to most prokaryotes.

Ann Intern Med, 1979 Apr, 90(4), 642 - 7
Ultrastructure of the Legionnaires' disease bacterium . A study using transmission electron microscopy; Chandler FW et al.; The Legionnaires' disease (LD) bacterium appeared ultrastructurally identical in human lung, egg yolk membrane, and artificial media, seen as a blunt or tapering rod measuring 0.3 to 0.9 micron in diameter and greater than or equal to 2.0 micron long . Greatly elongated forms were commonly found in cultures and yold sac membranes after 5 to 7 days of growth but were only rarely seen in human lung . The LD bacterium was clearly prokaryotic . Prominent features included electron-lucent nucleoids interspersed among areas of well-defined ribosomes; cleanly circumscribed cytoplasmic vacuoles or granular inclusions; and a double envelope enclosure, each portion consisting of a triple-layered "unit" membrane, approximately 75 A wide . Division always occurred as a pinching, nonseptate process typical of bacteria with a double, gram-negative type of envelope . No definite structure was seen in the periplasmic space that might represent the peptidoglycan layer . These features of the LD bacterium confirm earlier reports of the gram-negative staining reaction of organisms obtained from cultures and preliminary evidence of their gram-negative ultrastructure . We found no unique features that would aid in the ultrastructural differentiation of the LD bacterium from other small gram-negative bacilli.

Ann Intern Med, 1979 Apr, 90(4), 502 - 5
Microbiology of Legionnaires' disease bacterium; Isenberg HD; Legionnaires' disease bacterium in tissue does not readily react with the Gram stain but can be seen by other stains and direct immunofluorescence . It is a slow-growing, aerobic, gram-negative rod that can be cultivated over a narrow temperature range on Mueller-Hinton agar supplemented either with complex biological mixtures or certain ferric salts and cysteine . The bacterium produces unique, branched-chain fatty acids, catalase, oxidase (weakly), and gelatinase and uses starch while ignoring other carbohydrates . Pigment production is related to tyrosine in the medium . In-vitro studies suggest susceptibility to all antibiotics except vancomycin, but a class 1 beta-lactamase has been demonstrated . Analysis of DNA confirmed the unrelatedness of this bacterium to previously recognized prokaryotes . Diagnosis of the disease has depended largely on serologic test findings and the demonstration of the bacterium in tissue and, occasionally, on isolation . Additional, simpler, and more rapid diagnostic tests should soon be available.

Arch Microbiol, 1979 Mar 12, 120(3), 297 - 9
Pulvomycin, an inhibitor of prokaryotic protein biosynthesis; Assmann D et al.; Antibiotic 1063-Z isolated from culture fluids of Streptoverticillium mobaraense was identified as pulvomycin . Pulvomycin was observed to inhibit protein biosynthesis in growing cells of Bacillus brevis . The poly(U)-directed poly(Phe) synthesis in cell-free systems of Bacillus brevis and Escherichia coli was highly susceptible to the antibiotic . Pulvomycin did not affect the transfer of Phe to tRNA . The results suggest that the target of pulvomycin action is the polypeptide chain elongation.

Gene, 1979 Mar, 5(3), 197 - 206
Nomenclature of transposable elements in prokaryotes; Campbell A et al.; Transposable elements are defined as specific DNA segments that can repeatedly insert into a few or many sites in a genome . They are classified as simple IS elements, more complex Tn transposons and self-replicating episomes . Definitions and nomenclature rules for these three classes of prokaryotic transposable elements are specified.

Gene, 1979 Mar, 5(3), 179 - 96
Summary and critique of the new NIH guidelines for recombinant DNA research; Szybalski W; New NIH Guidelines for research involving recombinant DNA (R-DNA) molecules were issued on December 15, 1978 . These are composed of four main parts, the first defining R-DNA and specifying prohibitions and exemptions, the second describing physical and biological containment, the third assigning the containment levels for many R-DNA experiments, and the fourth detailing the roles and responsibilities of the investigator, research institutions and NIH . Although the new Guidelines reduce restrictions, principally on those R-DNA experiments that use Escherichia coli K-12 host-vector systems, and exempt from the Guidelines several classes of experiments on prokaryotes that naturally exchange their DNA, most of their provisions are unjustified by the present assessment of the absence of any practical risks; many totally innocuous experiments are unnecessarily restricted and even virtually prohibited mainly because no host-vector systems were officially certified . The term Guidelines is a misnomer since they are mandatory regulations, even without any statutory basis . They impose large but unnecessary bureaucratic burdens on scientists, research institutions, research committees and NIH, and represent unwarranted censorship of basic research, which is antithetical to the creativity of human thought, thus posing serious dangers to the traditional freedom of inquiry.

Biokhimiia, 1979 Mar, 44(3), 529 - 42
{Interaction of rat liver dexamethasone-receptor complexes with DNA}; Romanova NA et al.; Rat liver glucocorticoid-receptor complexes (GRC) acquire the ability to bind to DNA in a high affinity manner after activation by heating or precipitation with (NH)2SO4 . DNA is practically non-saturable by GRC in low salt buffers as well as in 0.15 M NaCl-containing buffer, although in the latter case the binding decreases approximately 3--5 times . GRC bind to homo- and heterologous prokaryotic DNA in a similar way; in both cases an addition of KCl (up to 0.15 M) to the medium is followed by the same decrease of the binding . This data suggest that the association of GRC with DNA observed in vitro is not accompanied by "recognition" of any certain DNA site . Besides DNA, activated GRC can associate with other polymers, charged positively (DEAE-cellulose) or negatively (RNA, polyvinylsulfate) . GRC interact very weakly with neutral compounds of the cellulose type but are strongly adsorbed on hydroxyapatite . Hence the activated GRC can be considered as an amphoteric protein . Salt solutions provoke dissociation of the GRC-DNA triple complexes: a complete dissociation is observed in the presence of 0,4 M NaCl or 0,4 M sodium phosphate buffer (pH 6,9) . Sodium phosphate buffer also elutes GRC from other sorbents such as DEAE-cellulose or hydroxyapatite . No significant dissociation of the GRC-DNA complexes is observed at sucrose concentration up to 2 M . The data obtained are indicative of an essential role of electrostatic forces for the interaction of GRC with DNA . The non-ionic detergent Triton X-100 at a concentration as low as 0,05% completely destroys the GRC-DNA triple complexes . The models explicating the selectivity of the genome activation by GRC without their "recognition" of any specific DNA sequences are proposed.

Proc Natl Acad Sci U S A, 1979 Mar, 76(3), 1251 - 5
Membrane biogenesis: cotranslational integration of the bacteriophage f1 coat protein into an Escherichia coli membrane fraction; Chang CN et al.; The coat protein (CP) of bacteriophage f1 is integrated into an Escherichia coli plasma membrane fraction consisting of inverted vesicles when it is synthesized in a cell-free, coupled transcription--translation system supplemented with the inverted vesicles . By using proteolytic enzymes as probes, we found by subsequent peptide mapping and determination of the sequence of the proteolytic products that CP was inserted into the inverted vesicles in an orientation indistinguishable from that in inverted vesicles prepared from infected E . coli: only a COOH-terminal portion of approximately 10 residues was accessible to proteolysis, whereas the remainder of CP (CP') was entirely protected . Protection of CP' was dependent on the integrity of the vesicle membrane, because it was abolished when proteolysis was done in the presence of nonionic detergents . Insertion was observed when the inverted vesicles were present during translation in the cell-free system, not when they were added after translation . Thus, the asymmetric insertion of this type of integral membrane protein is strictly coupled to translation . These findings are discussed with respect to prokaryotic membrane biogenesis and are related to bacteriophage f1 assembly and infection.

Proc Natl Acad Sci U S A, 1979 Feb, 76(2), 847 - 51
Molecular evolution of biomembranes: structural equivalents and phylogenetic precursors of sterols; Rohmer M et al.; Derivatives of one triterpene family, the hopane family, are widely distributed in prokaryotes; they may be localized in membranes, playing there the same role as sterols play in eukaryotes, as a result of their similar size, rigidity, and amphiphilic character . Their biosynthesis embodies many primitive features compared to that of sterols and could have evolved toward the latter once aerobic conditions had been established . Membrane reinforcement appears to be achieved in other prokaryotes by other mechanisms, involving either approximately 40-A-long rigid hydrocarbon chains terminated by one polar group acting like a peg through the double-layer or similar chains terminated by two polar groups acting like tie-bars across the membrane . These inserts can be tetraterpenes (e.g., carotenoids) . The biophysical function of membrane optimizers appears to have evolved toward sterols by changes limited to only a few enzymatic steps of the same fundamental biosynthetic processes.

Proc Natl Acad Sci U S A, 1979 Feb, 76(2), 717 - 21
Interesting and unusual features in the sequence of Neurospora crassa mitochondrial tyrosine transfer RNA; Heckman JE et al.; The mitochondrial tyrosine tRNA from Neurospora crassa has been sequenced and found to have several interesting features: (i) It resembles prokaryotic rather than eukaryotic tyrosine tRNAs in that it possesses a large variable loop (loop III); moreover, it can be quantitatively aminoacylated by Escherichia coli tyrosyl-tRNA synthetase but not by yeast tyrosyl-tRNA synthetase . (ii) This tRNA differs from all tRNA's sequenced to date in lacking the A residue at position 14 and the constant purine residue at position 15, two nucleosides that have been found so far in loop I of all tRNA's and that have been implicated in base-base tertiary interactions, respectively, with the universal U residue at position 8 and the constant pyrimidine residue at the end of loop III . (iii) Unlike the N . crassa mitochondrial initiator tRNA, this tRNA contains the usual TpsiC sequence in loop IV and the highly conserved GG sequence in loop I common to other tRNAs.

Hum Genet, 1979 Jan 25, 46(2), 209 - 17
Variability of bacterial gene-directed enzyme production in human genetically deficient cells; Horst J et al.; Human beta-galactosidase-deficient skin fibroblasts from a patient with generalized gangliosidosis (GMI-gangliosidosis type I) were treated with phage lambda plac DNA, coding for Escherichia coli beta-galactosidase (beta-D-galactoside galactohydrolase, EC.3.2.1.23) . New beta-galactosidase activity detected in cell extracts of phage DNA-treated GMI-gangliosidosis fibroblasts continued to vary considerably from one experiment to another . It behaved like the E . coli z-gene product upon immunochemical and physicochemical investigation . In some experiments the antigenic behavior of resultant beta-galactoside activity in lambda plac DNA-treated cells resembled that of mutant E . coli beta-galactosidase . Among the factors and variables that may be responsible for the variation in the results obtained here and elsewhere, low physical binding between prokaryotic mRNA sequences and fibroblast ribosomal RNA could play a part connected with effective translation . This hypothesis is discussed under the aspect of a comparison of the ribosomal binding site of lac z mRNA with the 3'-terminus of the eukaryotic 18s ribosomal RNA, which shows limited possibilities for base-pairing interactions . More extensive possibilities for forming Watson-Crick base pairs between their initiation site and the eukaryotic ribosomal binding site exist for other prokaryotic messengers, such as those of Q beta-replicase, f 1-coat protein, or UDPG-4-epimerase.

Symp Soc Exp Biol, 1979, 33, 9 - 36
Translocation of proteins across membranes: the signal hypothesis and beyond; Blobel G et al.; Proteins are translocated across membranes either coupled to translation (co-translationally) or after translation (post-translationally) . The information for both modes of translocation is encoded in the protein in the form of a short-lived sequence extension (signal sequence) . Additional information resides in the ribosome in the case of co-translational translocation, which proceeds via a ribosome--membrane junction . Translocation is mediated by specific receptors (ribosome and/or signal receptors) which are restricted in their location to distinct cellular membranes . In most cases the signal sequence is removed by a signal peptidase operating in an endoproteolytic mode . Membranes endowed with receptors for co-translational translocation are: the rough endoplasmic reticulum (RER) including the outer nuclear envelope membrane, the inner mitochondrial membrane and the thylakoid membrane of chloroplasts, in eukaryotic cells; and the plasma membrane in prokaryotic cells . Each of these membranes presumably contains a single distinctive signal receptor, ribosome receptor and signal peptidase . Membranes endowed with one distinct receptor each for post-translational translocation are both mitochondrial membranes, the chloroplast envelope membrane and the peroxisomal membrane . A signal sequence for co-translational translocation across the RER membrane that is identical in its secondary structure is shared by secretory, lysosomal and certain bitopic integral membrane proteins . Some integral membrane proteins presumably share another common sequence--referred to as stop-transfer sequence--which serves to interrupt translocation and thereby to orient the polypeptide chain in the lipid bilayer . Furthermore, the existence of a few specific 'sorting' sequences is postulated . These would be common to many proteins and would serve to route them to their final destination following translocation across or orientation within the membrane . Thus, the topological information which determines the intracellular pathway and the final location of a great number of proteins appears to reside in a small repertoire of specific sequences which are either a transient or a permanent part of the protein.

Biochimie, 1979, 61(2), 229 - 43
Effect of starvation on tRNA synthesis, amino acid pool, tRNA charging levels and aminoacyl-tRNA synthetase activities in the posterior silk gland of Bombyx mori L; Chavancy G et al.; Changes in the translational machinery components of the Bombyx mori posterior silk gland were analysed during starvation and refeeding and compared to the regularly fed larvae . During starvation, tRNA and ribosomal RNA synthesis are stopped . The amounts of different RNA classes and of the different tRNA species slow down at the same rate . Thus various tRNA show similar half-lifes and the preexisting tRNA adaptation to fibroin mRNA translation persists during starvation . Similarly, the tRNA/rRNA ratio is constant during starvation and refeeding (12 tRNA molecules for one ribosome) as in silk glands of control animals . Aminoacyl-tRNA synthetases and tRNA charging levels are decreased during starvation . The maximal tRNA charging level obtained during maximal protein synthesis in control animals is regained after 24 h refeeding of starved larvae . Changes observed in the free amino acid pool are not similar from one amino acid to another and levels reached after starvation do not differ strongly from the controls . Our results suggest that the production of translation apparatus components is coordinated and adjusted to the protein synthesis activity . Whether this coordination occurs in the silk gland is discussed on the basis of the "metabolic regulation", primarily described in prokaryotes and Yeast . Transfer RNA charging levels seem to play a key role in the process of regulation and could be implicated in the mechanism of tRNA adaptation if this phenomenon results as expected from a transcriptional control.

Am J Clin Pathol, 1979 Jan, 71(1), 43 - 50
Ultrastructure of the agent of Legionnaires' disease in the human lung; Chandler FW et al.; This report confirms the gram-negative ultrastructural characteristics of the Legionnaires' disease organism by direct examination of pulmonary tissue from six confirmed cases--two from the original Philadelphia epidemic of 1976 and four from more recent sporadic cases . All microorganisms seen in all six lungs were identical ultrastructurally and were predominantely within intra-alveolar macrophages, as previously observed by light microscopy . They appeared as short, blunt rods that were clearly prokaryotic; i.e., they had diffuse electron-lucent nucleoid areas interspersed among areas of well-defined ribosomes, a pinching nonseptic division, and enclosure within a double envelope consisting of two three-layer "unit" membranes, each approximately 75 A wide . This structure, together with a pinching division, is typical of gram-negative bacteria . The Legionnaires' disease organism multiples both intracellularly and extracellularly in tissue and has no unique ultrastructural features that would aid in its specific identification . These findings are compared with recent reports describing the ultrastructure of what was considered to be the Legionnaires' disease organism in yolk sac and culture medium, and in one human lung.

Scan Electron Microsc, 1979, (3), 549 - 64
Qualitative and quantitative aspects of labeling cell surface carbohydrates using lectins as probes; Lotan R; Lectins are proteins which bind mono- and oligosaccharides with great specificity . Many polysaccharides, glycoproteins and glycolipids which are important constituents of cell walls and surface membranes of prokaryotic and eukaryotic cells, contain sugar moieties with which lectins can interact . As a result lectins have been extensively used for the study of cell surface and membrane structure of their labeling . This paper reviews and evaluates the available methods for the preparation of fluorescent, electron-dense and radioactive lectin derivatives . The procedures involved in the visualization of lectin binding under light and electron microscopy are described . In addition, the methods for quantitative evaluation of the fluorescence on labeled cells and for analysis of the number of cell surface lectin binding sites using radioactively-labeled lectins are outlined . Examples are given for the application of fluorescent lectin derivatives for the detection of specific saccharide-containing molecules on the surfaces of living or fixed microbial cells and various normal and neoplastic cells . The use of lectins to demonstrate the dynamic nature of cell membranes and to detect changes in membrane structure or organization which occur or organization which occur during differentiation, development or after neoplastic transformation is discussed.

J Supramol Struct, 1979, 10(4), 397 - 404
Structure of functional A salina -- E coli hybrid ribosome by electron microscopy; Boublik M et al.; Small 40S Artemia salina and large 50S Escherichia coli ribosomal subunits can be assembled into 73S hybrid monosomes active in model assays for protein synthesis . The reciprocal combination -- small 30S E coli and large 60S A salina -- fails to form hybrids . The 73S hybrid particles strongly resemble homologous 70S E coli and 80S A salina monosomes . The morphologic differences between the corresponding eukaryotic and prokaryotic ribosomal particles, established by electron microscopy, do not significantly affect the assembly and mutual orientation of 40S A slina and 50S E coli subunits in the heterologous monosome . The fact that the structure of the interface, the supposed site of protein synthesis, is preserved in the active hybrid implies that retention or loss of biologic activity of hybrid ribosomes is determined by the extent of conformational changes in the interface.

Proc Natl Acad Sci U S A, 1979 Jan, 76(1), 381 - 5
Evolutionary change in 5S RNA secondary structure and a phylogenic tree of 54 5S RNA species; Hori H et al.; Secondary structure models of 54 5S RNA species are constructed based on the comparative analyses of their primary structure . All 5S RNAs examined have essentially the same secondary structure . However, there are revealing characteristic differences between eukaryotic and prokaryotic types . The prokaryotic 5S RNAs may be further classified into two types, one having 120 nucleotides (120-N type) and another having 116 (116-N type) . A possible mechanism for the conversion of the prokaryotic 116-N type to the 120-N type 5S RNAs (or vice versa) is discussed on the basis of their nucleotide alignments . Finally, by comparing the nucleotide alignments, we propose a phylogenic tree of the 54 5S RNA species.

Z Naturforsch {C}, 1979 Jan-Feb, 34(1-2), 33 - 7
Assimilatory nitrate reductase of Rhodopseudomonas capsulata AD2: a molybdo-hemeprotein; Alef K et al.; The assimilatory nitrate reductase of the phototrophic bacterium Rhodopseudomonas capsulata strain AD2 was purified to homogeneity by a combination of ammonium sulfate fractionation, chromatography on DEAE-cellulose and isoelectric focusing (isoelectric point of 4.8) . The purified enzyme was active only with reduced viologen dyes or reduced flavin as electron donors . Contrary to other bacterial assimilatory nitrate reductases, the enzyme was not inhibited by chlorate, but rather accepted this substance as an alternate substrate . The molecular weight of the enzyme was 185,000 dalton as determined by gelfiltration . Subunit analysis by sodium dodecyl sulfate (SDS) gel electrophoresis yielded a single protein band with a molecular weight of 85,000 dalton,, suggesting that the enzyme was composed of two identical subunits . The nitrate reductase contained 0.8 g-atoms molybdenum per 1.85 x 10(5) g protein and exhibited absorption maxima at 418, 523 and 552 nm in the reduced state (dithionite as reductant) . The nitrate reductase of Rps . capsulata AD2 is the first prokaryotic enzyme of the assimilatory type that has been shown to contain heme.

J Supramol Struct, 1979, 12(3), 299 - 304
Gliding mycoplasmas are inhibited by cytochalasin B and contain a polymerizable protein fraction; Maniloff J et al.; Studies are presented on the effect of cytochalasin B (CB) on the growth of five Mycoplasma species, three Acholeplasma species, and one Spiroplasma species . The three gliding mycoplasma species (M gallisepticum, M pneumoniae and M pulmonis are the only mycoplasmas inhibited by CB . These are the only prokaryotes reported to be inhibited by CB . This suggested that these three mycoplasmas might have some sort of cytoskeletal structure . A protein fraction has been isolated from M gallisepticum which polymerizes in 0.6 M KCl and depolymerizes when KCl is removed . This fraction contains a major 58,000-dalton protein, a 46,000-dalton protein, and a minor 87,000-dalton protein.

J Mol Evol, 1978 Dec 29, 12(2), 113 - 9
Bacteriophage MS2 RNA: a correlation between the stability of the codon: anticodon interaction and the choice of code words; Grosjean H et al.; The non-random distribution of degenerate code words in Bacteriophage MS2 RNA can be explained partially by considerations of the stability of the codon-anticodon complex in prokaryotic systems . Supporting this hypothesis we note that wobble codons are positively selected in codons having G and/or C in the first two positions . In contrast, wobble codons are statistically less likely in codons composed of A and U in the first two positions . Analyses of nucleotides adjacent to 5' and 3' ends of codons indicate a nonrandom distribution as well . It is thus likely that some elements of RNA evolution are independent of the structural needs of the RNA itself and of the translated protein product.

Biochemistry, 1978 Dec 26, 17(26), 5804 - 10
Involvement of the mature domain in the in vitro maturation of Bacillus subtilis precursor 5S ribosomal RNA; Meyhack B et al.; A precursor of 5S ribosomal RNA from Bacillus subtilis (p5A rRNA, 179 nucleotides in length) is cleaved by RNase M5, a specific maturation endonuclease which releases the mature 5S rRNA (m5, 116 nucleotides) and precursor fragments derived from the 5' (21 nucleotides) and 3' (42 nucleotides) termini of p5A rRNA . Previous results (Meyhack, B., et al . (1978) Proc . Natl . Acad . Sci . U.S.A . 75, 3045) led to the conclusion that recognition elements in potential RNase M5 substrates mainly reside in the mature moiety of the precursor . Limited digestion of p5A rRNA with RNase T1 permitted the isolation of a number of test substrates which contained both precursor-specific segments and were unaltered in the immediate vicinity of the cleavage sites, but which differed in that more or less extensive regions of the mature moiety of the p5A rRNA were deleted . Tests of the capacity of these partial molecules to serve as substrates for RNase M5 indicate clearly that the enzyme recognizes the overall conformation of potential substrates, neglecting only the double-helical "prokaryotic loop" (Fox, G.E., & Woese, C.R . (1975) Nature (London) 256, 505).

Science, 1978 Dec 22, 202(4374), 1257 - 60
Implications of RNA-RNA splicing in evolution of eukaryotic cells; Darnell JE Jr; The differences in the biochemistry of messenger RNA formation in eukaryotes compared to prokaryotes are so profound as to suggest that sequential prokaryotic to eukaryotic cell evolution seems unlikely . The recently discovered noncontiguous sequences in eukaryotic DNA that encode messenger RNA may reflect an ancient, rather than a new, distribution of information in DNA and that eukaryotes evolved independently of prokaryotes.

Biochim Biophys Acta, 1978 Dec 21, 521(2), 459 - 69
Studies on the mode of action of hygromycin B, an inhibitor of translocation in eukaryotes; Gonzalez A et al.; Hygromycin B is an unusual aminoglycoside antibiotic active against both prokaryotic and eukaryotic cells . Hygromycin B at 0.38 mM concentration completely halts yeast cell growth in rich media, presumably by preventing protein synthesis by cytoplasmic ribosomes . Polypeptide synthesis in cell-free extracts from rabbit reticulocytes, wheat germ and yeast is strongly blocked by low concentrations of hygromycin B . The antibiotic inhibits peptide chain elongation by yeast polysomes by preventing elongation factor EF-2-dependent translocation, although it does not affect either the formation of the EF-2-GTP-ribosome complex or the EF-2- and ribosome-dependent GTP hydrolysis which takes place uncoupled from translocation . The inhibition of translocation by hygromycin B might result from the stabilization of peptidyl-tRNA bound to the ribosomal acceptor site, since the stability of {3H}Phe-tRNA-EF-1-poly(U)-ribosome and {3H}Phe-tRNA-poly(U)-ribosome complexes is increased in the presence of hygromycin B . The inhibition of polyphenylalanine synthesis by reticulocyte ribosomes and enzymic translocation of peptidyl-tRNA by yeast polysomes can be reversed by increasing concentrations of EF-2 suggesting a relationship between the binding sites of EF-2 and hygromycin B on the ribosome . Neither non-enzymic translocation, that takes place in the presence of high potassium concentrations, nor the peptide bondforming step are affected by hygromycin B.

Mol Gen Genet, 1978 Nov 9, 166(3), 291 - 7
Eukaryotic ribosomal proteins stimulate Escherichia coli stringent factor to synthesize guanosine 5'-diphosphate, 3'-diphosphate (ppGpp) and guanosine 5'-triphosphate, 3'-diphosphate (ppGpp); Martini O et al.; When supplemented with Escherichia coli stringent factor, 80S ribosomes from various sources failed to support guanosine tetra- and pentaphosphate ((p)ppGpp) synthesis . In contrast, ribosomal proteins from 80S, 60S or 40S particles (mouse embryos, rabbit reticulocytes) crossreacted with the E . coli stringent factor . Significant stimulation of (p)ppGpp synthesis was achieved with a concentration as low as 5 micrograms of ribosomal proteins/ml . These observations may provide additional crtieria to detect homologies between eukaryotic and prokaryotic ribosomal proteins.

Bull Soc Pathol Exot Filiales, 1978 Nov-Dec, 71(6), 412 - 6
{Presence of a prokaryote of the genus Haemobartonella Tyzzer and Weinman, 1939, in the blood of Nigerians in the Niamey region}; Gretillat S et al.; The hemograms of 97 bed-riddens in very bad conditions reveal the presence (74 more or less infected but 6 heavily) of cocci, rots, rings, commas, coloured by May-Grunwald and Giemsa stain against the cell membrane wall of the erythrocyts and sometimes free in the blood plasma . This procaryotic element is the same agent of the canine, feline, equine and cuniculine haemobartonellosis in Niger . Principal symptoms are general weariness, anaemia, arthralgies, dizziness, anguish, suffocation crisis . It is a disease of the deficient and underfed men in Sahel.

Proc Natl Acad Sci U S A, 1978 Nov, 75(11), 5324 - 8
Pulvomycin, an inhibitor of protein biosynthesis preventing ternary complex formation between elongation factor Tu, GTP, and aminoacyl-tRNA; Wolf H et al.; Pulvomycin and the synonymous antibiotics labilomycin and 1063-Z are shown to inhibit prokaryotic protein synthesis by acting on elongation factor Tu (EF-Tu): in the presence of the antibiotic, the affinity of EF-Tu for guanine nucleotides is altered, the EF-Tu.GDP/GTP exchange is catalyzed, and the formation of the EF-Tu.GTP complex is stimulated . Hydrolysis of GTP by EF-Tu, induced by aminoacyl-tRNA, ribosomes, and mRNA or by kirromycin, is inhibited by pulvomycin . As shown by Millipore filtration, chromatographic analysis, and hydrolysis protection experiments, pulvomycin prevents interaction between aminoacyl-tRNA and EF-Tu.GTP to yield the ternary complex aminoacyl-tRNA.EF-Tu.GTP . Thus, enzymatic binding of aminoacyl-tRNA to ribosomes is blocked.

Biochemistry, 1978 Oct 3, 17(20), 4260 - 5
Physical properties of Artemia salina ribosomes; Nieuwenhuysen P et al.; Eukaryotic ribosomes were isolated from the cryptobiotic embryos and from the further-developed free-swimming nauplii of the brine shrimp Artemia salina . Analytical boundary sedimentation and photon correlation spectroscopy yielded, respectively, the standard sedimentation and diffusion coefficients at infinite dilution, s degrees 20,w = 81 +/- 1 S and D degrees 20,w = (1.41 +/- 0.02) x 10(-7) cm2/s, for the unfixed and formaldehyde-fixed ribosomes from different developmental stages and for ribosomes attached to a messenger RNA fragment . Also, the density increment was determined, from which the partial specific volume was derived (0.63 +/- 0.01 cm3/g) . Combination of the different measured parameters gives accurate values for the molecular weight (3.8 +/- 0.1) x 106 and for size and solvation parameters . These results are compared with their counterparts for the smaller ribosomes from the prokaryote Escherichia coli.

Lipids, 1978 Oct, 13(10), 686 - 91
Sterol-polyene antibiotic complexation: probe of membrane structure; Bittman R; Polyene antibiotics are useful tools for studying the role of sterols in biological membranes . The interaction of polyene antibiotics with membrane-bound sterols in artificial membrane systems, prokaryotic and eukaryotic cells, and lipid-containing viruses is reviewed . The pentaene macrolide, filipin, is shown to serve as a probe of phosphatidylcholine-sterol interaction and of the localization of cholesterol in the membrane of mycoplasmas.

Proc Natl Acad Sci U S A, 1978 Oct, 75(10), 4901 - 5
Laser Raman evidence for new cloverleaf secondary structures for eukaryotic 5.8S RNA and prokaryotic 5S RNA; Luoma GA et al.; Neither of the two previously proposed secondary structures for eukaryotic 5.8S RNA is consistent with the present laser Raman results . A new, highly stable "cloverleaf" secondary structure not only fits the Raman data but also accounts for previously determined enzymatic partial cleavage patterns, base sequence and pairing homologies, and G-C and A-U base pair numbers and ratios . The new cloverleaf model also conserves several structural features (constant loops, bulges, and stems) consistent with known 5.8S RNA functions . Finally, we propose a similar new cloverleaf secondary structure for Escherichia coli 5S RNA, consonant with many known properties of prokaryotic 5S RNA.

Nucleic Acids Res, 1978 Oct, 5(10), 3715 - 29
The turnover of tRNAs microinjected into animal cells; Schlegel RA et al.; Red cell-mediated microinjection has been used to study tRNA turnover in SV3T3 mouse cells and TC7 cells, an African green monkey kidney line . The turnover of endogenous tRNA, measured by labeling with 3H-methionine, was first-order with half-lives of approximately one day in SV3T3 and two days in TC7 cells . 32PtRNA isolated from E . coli or TC7 cells turned over at the same rate as endogenous tRNA when injected into either SV3T3 or TC7 cells . This demonstrates that cellular processes, not properties inherent to tRNAs, are responsible for the difference in tRNA turnover observed between SV3T3 and TC7 cells . These results further indicate that the mechanism of tRNA turnover in mammaliam cells does not distinguish prokaryotic from eukaryotic tRNAs . In contrast to unmodified tRNA, glyoxalated tRNA was rapidly degraded upon injection . Thus altered tRNA's, like altered proteins, are turned over more rapidly in animal cells.

Biochim Biophys Acta, 1978 Sep 27, 520(2), 419 - 27
Neurospora crassa mitochondrial transfer RNAs; De Vries H et al.; Total mitochondrial tRNA from Neurospora crassa was characterized by base composition analysis, one- and two-dimensional gel electrophoreses and reversed-phase chromatography on RPC5 . The guanosine + cytidine content was about 43%, as compared to 60% for cytoplasmic tRNA . The modified nucleoside content was low and about the same as that of total yeast mitochondrial tRNA, though the G + C content is very different . We found psi, T, hU, t6A, m1G, M2G, m22G . Neither the eukaryotic "Y" base, nor the prokaryotic s4U were present . On two-dimensional polyacrylamide gel electropherograms about 25 species were separated . One species for phenylalanine, two for leucine and two for methionine could be located . Neurospora crassa mitochondrial tRNA does not hybridize with yeast mitochondrial DNA.

Arch Microbiol, 1978 Sep 1, 118(3), 235 - 41
Isolation, characterization, and numerical taxonomy of Simonsiella strains from the oral cavities of cats, dogs, sheep, and humans; Kuhn DA et al.; Forty-nine strains of the gliding prokaryote Simonsiella were isolated from the oral cavities of cats (8), dogs (19), sheep (4), and humans (18) in Southern California by a direct isolation procedure using a complex serum-enriched medium . The numerical taxonomic analysis (unweighted pair-group method using arithmetric averages) of 57 differential traits for each strain was based on standard bacteriological diagnostic tests and included the molar guanine-plus-cytosine contents of the DNA and the relative percentages of fatty acid contents reported earlier . The resulting phenogram clustered the strains of Simonsiella into groups that correlated with sources of origin . The study included the neotype strain of Simonsiella crassa (ATCC 27504, ICPB 3651, NCTC 10283) of Australian sheep origin . The strains isolated from dogs, sheep, and humans form clusters of organisms that appear to have become adapted to live in and possibly to have evolved with their respective "hosts" . In our judgment, these source-of-origin clusters represent different "ecospecies".

Biochemistry, 1978 Aug 22, 17(17), 3587 - 91
Rotational relaxation of 1,6-diphenylhexatriene in membrane lipids of cells acclimated to high and low growth temperatures; Martin CE et al.; Measurement of the time-resolved fluorescence depolarization of 1,6-diphenylhexatriene (DPH) in artificial bilayers of microsomal membrane lipids from Tetrahymena gives detailed information concerning the molecular motion of this probe and fluid properties of the membrane lipids which are obscured with steady-state methods . The rotational motion of DPH in these lipids from cells acclimated to 15 and 39.5 degrees C growth temperatures was anisotropic, which agrees with recent time-resolved studies of this probe in synthetic phospholipid systems . Evaluation of DPH polarization data obtained from these lipid fractions at their respective growth temperatures showed differences in physical properties which suggest that "viscosity", per se, of the microsomal lipids is not a strictly regulated as it is in prokaryotic systems . Rotational relaxation of DPH in 39.5 degrees C microsomal lipids measured at 15 degrees C is more complex than that of either lipid fraction measured at its actual growth temperature, suggesting that the probe has partitioned into two dissimilar environments within the bilayer . Similar effects are observed in the microsomes of 39.5 degrees C cells by freeze-fracture electron microscopy following rapid cooling to 15 degrees C . Under these conditions, two distinct regions are observed on the fracture faces, suggesting a correlation between lipid phase changes and alterations in membrane structure.

Science, 1978 Aug 4, 201(4354), 444 - 5
Light-stimulated morphogenesis in the fruiting myxobacterium Stigmatella aurantiaca; Qualls GT et al.; When the fruiting myxobacterium Stigmatella aurantiaca, a gliding prokaryote, is starved on an agar surface, the cells form multicellular aggregates resulting from morphogenetic movements . In the presence of incandescent light, each aggregate develops into a structurally complex fruiting body, possessing a stalk and several sporangia . In contrast, this pattern of development is not seen when cultures are incubated in the dark . The cells form irregular interconnecting aggregates, which rarely develop into fruits . However, aggregates formed in the light will develop into fruits even if placed in the dark, suggesting that the light produced a relatively stable alteration in the phenotype of the cells.

J Pediatr, 1978 Jul, 93(1), 106 - 9
Intracellular deoxyribonucleic acid--modifying activity of intermittent phototherapy; Santella RM et al.; Phototherapy is capable of damaging the genetic material of eukaryotic and prokaryotic cells at fluences considerably less than that received by irradiated infants . It has been suggested that intermittent phototherapy, with varying on-off cycles, may offer theoretical advantages since the total light dosage received by the exposed infant is reduced . The present study was undertaken to determine the effect of intermittent phototherapy on the genetic material of human cells in tissue culture . Intermittent illumination produced more DNA damage than a similar light dosage administered continuously . These results suggest that intermittent phototherapy regimens may prove more deleterious to irradiated infants than continuous phototherapy.

Gene, 1978 Jul, 3(4), 315 - 31
Analysis of transposable elements inserted in the genomes of bacteriophages Mu and P1; De Bruijn FJ et al.; We have examined the genomes of the temperate bacteriophages Mu and P1 and some of their insertion mutants for hybridization with the prokaryotic transposable elements IS1 and IS2 . We used the DNA blotting-hybridization technique in which denatured DNA fragments are transferred to nitrocellulose paper directly from agarose gels and hybridized to 32P-labeled probe DNA . The 800 base pair insertion in an X mutant of Mu was found to hybridize with IS1 . The chloramphenicol resistance transposon, Tn9, in Mu X cam mutants was found to be located at or close to the sites of IS1 insertion in X mutants; Tn9 also hybridized with IS1 . The restriction endonuclease BalI cleaved IS1 once; it cleaved Tn9 in all Mu X cam mutants twice to release a fragment of about 1700 base pairs . These results support the conclusion that Tn9 contains one copy of IS1 at each end . In the P1cam isolate, from which Tn9 was transposed to Mu, BalI made a third cut in Tn9 giving rise to fragments of about 850 base pairs . The data further suggested that Tn9 is present in tandem copies in the P1cam isolate we examined . P1 itself was found to harbor IS1 . The two P1 strains tested had a common fragment containing IS1; one strain had an additional copy of IS1 . The IS1 element common to the P1 strains was shown to be the site of the Tn9 insertion in the P1cam isolate examined . No hybridization between IS2 and any of the Mu and P1 strains could be detected.

Science, 1978 Jun 9, 200(4346), 1118 - 24
Microtubules in prokaryotes; Margulis L et al.; Longitudinally aligned microtubules, about 220 A in diameter, have been seen in the protoplasmic cylinders of the following spirochetes (symbiotic in the hindguts of dry-wood and subterranean termites): Pillotina sp., Diplocalyx sp., Hollandina sp . They are also present in a gliding bacterium from Pterotermes occidentis . These microtubules are probably composed of tubulin, as determined by staining with fluorescent antibodies to tubulin and comigration with authentic tubulin on acrylamide gels . Treponema reiteri lack tubulin by these same criteria . These observations support the hypothesis of the symbiotic origin of cilia and flagella from certain spirochetes.

Nucleic Acids Res, 1978 Jun, 5(6), 2153 - 67
DNA-methylase from regenerating rat liver: purification and characterisation; Simon D et al.; DNA methylase has been purified 660-fold from nuclei from regenerating rat liver . The enzyme is able to methylate single stranded (ss) and double stranded (ds) DNA, the only reaction product being 5-methylcytosine . Previously unmethylated double stranded DNA from prokaryotes (M.luteus) as well as from eukaryotes (Ascaris suis) can serve as substrates . The synthetic copolymers (dG-dC)n . (dC-dG)n and (dG,dC)n are also methylated . While SV40 DNA is almost not methylated, PM2 DNA is a good substrate even in the supercoiled form . The enzyme methylates 1 in 17 bases in heterologous M.luteus DNA, but only 1 in 590 in homologous rat liver DNA . The high methylation level of M.luteus DNA, an analysis of the methylated pyrimidine isostichs and a preliminary dinucleotide analysis suggest that all the CpGs in a DNA can be methylated.

Can J Biochem, 1978 Jun, 56(6), 440 - 3
The evolution of 5S RNA secondary structures; Sankofff D et al.; We have applied the Pipas-McMahon algorithm based on free energy calculations to the search for a 5S RNA base-pair structure common to all known sequences . We find that a 'Y' shaped model is consistently among the structures having the lowest free energy using 5S RNA sequences from either eukaryotic or prokaryotic sources . Compaison of this 'Y' structure with models which have recently been proposed show these models to be remarkably similar, and the minor differences are explicable based on the technique used to obtain the model . That prokaryotic and eukaryotic 5S RNA can adopt a similar secondary structure is strong support for its resistance to change during evolution.

Biokhimiia, 1978 Jun, 43(6), 947 - 58
{Plant histones . Relevance to the evolution of prokaryotes to eukaryotes}; Gofshtein LV; There are many procaryotic and eucaryotic organisms in plant kingdom . It is hoped that the study of plant histones will be useful in evolutionary studies . The histones of great variety of animal species have been studied and well characterized . Less information is available concerning plant histones . The general conclusion drawn from these investigations is that most organisms of eucaryotic plant and animal species contain the same five major histone fractions . Recently the histone-like proteins were found in some primitive eucaryotes and procaryotes . Data on histones from higher and lower eucaryotes and histone-like proteins of procaryotes are reviewed . Evolution of histones and their appearance prior to that of eucaryotic cell is postulated . The role of histones in evolution of nucleosomes is discussed.

Proc Natl Acad Sci U S A, 1978 Jun, 75(6), 2859 - 63
Conservation of ribosomal protein binding sites in prokaryotic 16S RNAs; Thurlow DL et al.; The Escherichia coli 30S ribosomal subunit proteins S4, S7, S8, S15, S17, and S20 that interact independently with 16S RNA from E . coli formed specific heterologous complexes with 16S RNAs extracted from 11 different prokaryotes covering a broad phylogenetic range . Complex formation was shown to be specific by saturation of binding in the presence of excess protein . Binding stoichiometries and the apparent affinities for a given protein varied depending on which 16S RNA was used, although the pattern of binding was not strictly correlated with phylogenetic relationships . The size-distribution of fragments resulting from limited hydrolysis of free prokaryotic 16S RNAs with T1 and pancreatic ribonucleases indicated that the structural organization of 16S RNA from E . coli is similar to that of 16S RNAs from closely related species, but differs, although to an unknown extent, from that of 16S RNAs from other prokaryotes tested . Digestions of RNA-protein complexes under similar conditions indicated that the proteins remain bound to specific RNA fragments . For those 16S RNAs isolated from species closely related to E . coli, the fragments were comparable to those generated by hydrolysis of the homologous complex.

Proc Natl Acad Sci U S A, 1978 Jun, 75(6), 2829 - 33
Comparison of Artemia salina and Escherichia coli ribosome structure by electron microscopy; Boulik M et al.; The structure of eukaryotic Artemia salina and prokaryotic Escherichia coli ribosomes has been compared by electron microscopy . Despite the established differences in size and in the amount and proportion of the protein and RNA moieties, both types of ribosomes appear to have substantial similarity in the overall shape and in the mutual orientation of the subunits on the monosome . The small subunit is located in the "crown" region of the large subunit lengthwise between the two side crests . However, high-resolution electron microscopy reveals distinct differences in the fine structure of both small and large subunits . The 40S A . salina subunit with three structural domains is more complex than the corresponding E . coli subunit . The 60S A . salina subunit has a less expressed "crown" region and shows a knob-like protrusion in the base . Structural asymmetry is a characteristic feature common to subunits and monosomes from both A . salina and E . coli.

Proc Natl Acad Sci U S A, 1978 May, 75(5), 2190 - 4
Homologous nucleotide sequences between prokaryotic and eukaryotic mRNAs: the 5'-end sequence of the mRNA of the lipoprotein of the Escherichia coli outer membrane; Pirtle RM et al.; The sequence of the first 89 nucleotides at the 5' end of the mRNA for the lipoprotein of the Escherichia coli outer membrane is: GCUACAUGGAGAUUAACUCAAUCU-AGAGGGUAUUAAUAAUGAAAGCUACUAAACUGGUACU-GGGCGCGGUAAUCCUGGGUUCUACUCUG . The sequence of the first 72 nucleotides was established by direct sequencing methods and was extended to 89 residues on the basis of the known sequences of oligonucleotides obtained from complete digestion of the mRNA by ribonuclease T1 or A and the known amino acid sequence of the prolipoprotein . The mRNA has an untranslated region of 38 residues before the initiation codon, AUG . A unique feature of the 5'-end sequence of the mRNA is that the sequence of 12 nucleotides (GUAUUAAUAAUG) prior to, and including, the initiation codon is the same as that found at the ribosome-binding site for 80S ribosomes in brome mosaic virus RNA4, a eukaryotic mRNA {Dasgupta, R., Shih, D., Saris, C . & Kaesberg, P . (1975) Nature 256, 624-628}.

Biosystems, 1978 Apr, 10(1-2), 37 - 53
Modified bases in the DNAs of unicellular eukaryotes: an examination of distributions and possible roles, with emphasis on hydroxymethyluracil in dinoflagellates; Rae PM et al.; The occurrence of small amounts of one or more of several modified bases in the DNA of an organism is widespread in nature . Prominent among these bases are 5-methylcytosine, N6-methyladenine and 5-hydroxymethyluracil . All can be found in varying amounts in DNA of viral, prokaryotic and eukaryotic origin . In some organisms, modified nucleotides comprise a large fraction of DNA nucleotides and in others there is complete replacement of one of the common four nucleotides by a modified one . This article discusses the distributions and possible roles of the several modified bases found in prokaryote and eukaryote DNAs . Emphasis is given (1) methylcytosine in a broad variety of eukaryotes, (2) methyladenine in certain protozoa and protophyta and (3) hydroxymethyluracil in dinoflagellates . Attention is focused on the phenomenology and the possible consequences of the presence of hydroxymethyluracil in DNA.

J Gen Microbiol, 1978 Apr, 105(2), 335 - 42
Dimethyl sulphoxide reduction by micro-organisms; Zinder SH et al.; Dimethyl sulphoxide (DMSO) was reduced to dimethyl sulphide by a wide variety of micro-organism, including prokaryotes and eukaryotes, aerobes and anaerobes . Dimethyl sulphone was not reduced by any of the organisms tested . Cell-free extracts of Escherichia coli reduced DMSO using reduced pyridine nucleotides as electron donors . Activity was greater in anaerobically grown cells than in those grown aerobically . Two other sulphoxides, methionine sulphoxide and tetramethylene sulphoxide, substantially inhibited DMSO reduction by extracts . Mutants of E . coli, which were unable to reduce biotin sulphoxide to biotin, were tested for their ability to reduce DMSO in whole cells and extracts . These mutants were in four different gene loci, bisA to bisD . DMSO reductase activity of the mutants was generally less than that of the wild-type strain, and activity depended upon the gene locus involved, the growth medium and the growth conditions . Only the bisA mutant had very low activity under all conditions . All of the bis mutants were able to grow using methionine sulphoxide as a sulphur source, indicating that biotin sulphoxide and methionine sulphoxide are reduced by different enzyme systems . DMSO may be reduced by both of these enzyme systems.

Biochemistry, 1978 Mar 21, 17(6), 1015 - 27
Comparative kinetic studies of cytochromes c in reactions with mitochondrial cytochrome c oxidase and reductase; Errede B et al.; Kinetic studies of the reactions of selected eukaryotic and prokaryotic cytochromes c with mitochondrial cytochrome c oxidase (ferrocytochrome c:oxygen oxidoreductase (EC 1.9.3.1) using a standardized complex IV preparation from beef heart are reported . Data on reactions with NADH-linked cytochrome c reductase (complexes I and III) are included . The concentration ranges employed provide a basis for quantitative demonstration of a general rate law applicable to oxidase reactions of cytochrome c of greatly differing reactivities . Results are interpreted on the basis of a modified Minnaert mechanism (Minnaert, K . (1961) Biochim . Biophys . Acta 50, 23), assuming productive complex formation between cytochrome c and free oxidase in addition to further complex binding of a second cytochrome c molecule to the initially formed oxidase complex . Kinetic constants so obtained are consistent with the assumption that binding is the dominant parameter in reactivity, and can be rationalized most simply on this basis.

Biochem J, 1978 Mar 1, 169(3), 633 - 41
Purification and characterization of the class-II D-fructose 1,6-bisphosphate aldolase from Escherichia coli (Crookes' strain); Baldwin SA et al.; A new form of the class-II D-fructose 1,6-bisphosphate aldolase (EC 4.1.2.13) of Escherichia coli (Crookes' strain) was isolated from an extract of glycerol-grown bacteria . It has a higher molecular weight (approx . 80000)than previous preparations of the enzyme and closely resembles the typical class-II aldolase from yeast in size and amino acid composition . On the other hand, its kinetic behaviour is not typical of a class-II aldolase . The enzyme has no requirement for thiol compounds either for stability or activity, added K+ ions have no effect, and the optimum pH for the cleavage activity is unusually high . The class-II enzymes from the prokaryote E . coli and the eukaryote yeast show no immunological identity . However, the similarity of their structures suggests that they have evolved from a common ancestor.

Biochem J, 1978 Mar 1, 169(3), 643 - 52
Novel kinetic and structural properties of the class-I D-fructose 1,6-bisphosphate aldolase from Escherichia coli (Crookes' strain); Baldwin SA et al.; Investigation of aldolase 1, the class-I D-fructose 1,6-bisphosphate aldolase (EC4.1.2.13) from Escherichia coli (Crookes' strain), showed it to have unusual kinetic and structural properties . The enzyme appeared to be larger than was previously supposed and may be a decamer with a mol . wt . of approx . 340000 . Its fructose 1,6-bisphosphate-cleavage activity was unaffected by these compounds . The enhancement exhibited a strong dependence on pH . These novel kinetic properties do not seem to be shared by any other fructose 1,6-bisphosphate aldolase, but recall the activation by polycarboxylic acids of the deoxyribose 3-phosphate aldolases from some other organisms . In view of its unusual properties, it is unlikely that aldolase 1 from E . coli is closely related to the class-1 aldolases that have been detected in several other prokaryotes, or to the typical class-1 enzymes from eukaryotes.

Eur J Biochem, 1978 Mar, 84(1), 197 - 205
beta-Lapachone, an inhibitor of oncornavirus reverse transcriptase and eukaryotic DNA polymerase-alpha . Inhibitory effect, thiol dependence and specificity; Schuerch AR et al.; beta-Lapachone is a naturally occuring compound that can be isolated from a number of tropical trees . It is shown to be a potent inhibitor of reverse transcriptase activity from both avian myeloblastosis virus and Rauscher murine leukaemia virus . In addition, it affects eukaryotic DNA-dependent DNA polymerase-alpha activity: 50% inhibition is reached in 60-min incubation time by about 8 micron beta-lapachone . Enzyme activity is inhibited irrespective of the purity of the enzyme used or of the amount or type of template/primer or substrate present . The inhibitory effect of the drug is only observed in the presence of dithiothreitol . The primary site of action of beta-lapachone appears to be the enzyme protein, as is also borne out by the specificity of its action . Eukaryotic DNA-dependent DNA polymerase-beta, prokaryotic DNA-dependent DNA polymerase I, several other nucleic acid polymerases and some completely unrelated enzymes are not affected . Reverse transcriptase and DNA-dependent DNA polymerase-alpha may be in someway related in possessing similarly exposed '--SH structures' in their active sites . beta-lapachone thus affords a novel means of studying such interrelationships and of further characterizing enzymes.

J Mol Evol, 1978 Feb 21, 10(4), 283 - 91
Ribosomal RNA homologies and the evolution of the filamentous blue-green bacteria; Bonen L et al.; Ribosomal RNA (rRNA) sequence homology (as determined by comparisons of T1 oligonucleotide catalogs of 32P-labeled 16S rRNAs) has been used to assess phylogenetic relationships within the filamentous and unicellular blue-green bacteria, and to identify regions of evolutionary conservatism within blue-green bacterial 16S rRNAs . Nostoc and Fishcherella, representatives of two morphologically distinct and highly differentiated orders, are shown to be as closely related (on the basis of RNA sequence homology) as typical members of the non-blue-green bacterial genus Bacillus . They are further shown to be (on the same basis) indistinguishable from typical unicellular members of a subgroup of the unicellular blue-green bacterial order Chroococcales . These results have general implications for studies of the origin of differentiated prokaryotes and of evolutionary change in prokaryotic macromolecules . In particular, they provide indirect evidence that the divergences of contemporary major prokaryotic groups are truly ancient ones.

Biochem J, 1978 Feb 15, 170(2), 203 - 10
Studies on sex-organ development . Changes in chromatin structure during spermatogenesis in maturing rooster testis as demonstrated by the initiation pattern of ribonucleic acid synthesis in vitro; Mezquita C et al.; To probe the structural change in the genome of the differentiating germ cell of the maturing rooster testis, the chromatin from nuclei at various stages of differentiation were transcribed with prokaryotic RNA polymerase from Escherichia coli or with eukaryotic RNA polymerase II from wheat germ . The transcription was performed under conditions of blockage of RNA chain reinitiation in vitro with rifampicin or rifampicin AF/013 . With the E . coli enzyme, the changes in (1) the titration curve for the enzyme-chromatin interaction, (2) the number of initiation sites, (3) the rate of elongation of RNA chains, and (4) the kinetics of the formation of stable initiation complexes revealed the unmasking of DNA in elongated spermatids and the masking of DNA in spermatozoa . In both cases the stability of the DNA duplex in the initiation region for RNA synthesis greatly increased . In contrast with the E . coli enzyme, the wheat-germ RNA polymerase II was relatively inefficient at transcribing chromatin of elongated spermatids . Such behaviour can be predicted if unmasked double-stranded DNA is present in elongated spermatids.

Microbios, 1978, 22(88), 103 - 33
Pillotinas and hollandinas: distribution and behaviour of large spirochaetes symbiotic in termites; To L et al.; Pillotina spirochaetes have been observed in the hindguts of wood-eating cockroaches (Cryptocercus punctulatus), and in 25 out of 28 species of termites examined . They were especially abundant in 21 species of dry wood termites of the family Kalotermitidae, from Europe, North America and Australia . These included many species of Kalotermes and one or a few of the following: Glyptotermes, Bifidotermes, Neotermes, Ceratokalotermes, Paraneotermes, Cryptotermes, Porotermes, Marginitermes, Pterotermes, Zootermopsis, Reticulitermes, Coptotermes, Heterotermes, and nasutitermitids . Identifications of pillotinas were made on the basis of large size (0.5--2 micromtere in diameter, 50 to greater than 100 micrometers in length) and wave pattern; these were verified by electron microscopy in K . schwarzi, Pterotermes occidentis and others . Pillotinas were also present in all species of subterranean termites (Family Rhinotermitidae) examined, and in the most primitive Australian termite, Mastotermes darwiniensis (Family Mastotermitidae) . They were not observed in damp wood termites (Family Hodotermidiae) . Pillotinas are invariably associated with a rich, complex xylophagous microbial community composed primarily of motile prokaryotes, and hypermastigote and polymastigote flagellates . Some have been previously described by those primarily concerned with termite hindgut protozoa . Observations were made on their modes of behaviour, division, and microbial associates . A new genus of spirochaetes, Hollandina, is also described . It is distinguished from Pillotina by a smaller size and several ultrastructural features, but is otherwise closely related taxonomically . Evidence is provided to support Hollande and Gharagozlou's (1967) concept that the pillotinas and hollandinas deserve the taxonomic status of 'family' and that they should be classified with the cristispire siprochaetes a-cording to the scheme developed by Hovind-Hougen (1976) . Spirochaetes are treated as a Phylum of the Kingdom Monera (Prokaryota) in the five kingdom system of Whittaker (1969).

Acta Biochim Pol, 1978, 25(2), 129 - 46
Protein synthesizing system from wheat germ: efficient translation of synthetic and natural messages; Rychlik W et al.; Optimum conditions for translation of eukaryotic, prokaryotic and synthetic templates in wheat germ cell-free extract were determined . 1 . Translation of eukaryotic message (BMV RNA and TMV RNA) was at optimum at the same concentrations of K+, Mg(2+), HEPES and spermine . In optimal conditions the efficiency of translation was high, for BMV RNA being equal to 220 pmoles and for TMV RNA, to 280 pmoles of leucine incorporated per 1 microgram of template . Prokaryotic template (Qbeta RNA) was translated under different ionic conditions . 2 . Translation of synthetic template {poly(U)} was at optimum at fairly higher concentrations of K+ and Mg(2+) than those optimal for natural template translation . 3 . Efficient translation of natural and synthetic templates depends on complete removal of inhibitors found in the wheat germ cell-free extract . Action of these inhibitors could be mimicked by adenine nucleotides.

Bull Cancer, 1978, 65(3), 283 - 97
Formation of thymine containing dimers in skin exposed to ultraviolet radiation; Johnson BE; Nuclear DNA appears to be the major molecular target for the inhibitory, mutagenic and lethal effects of ultraviolet radiation on cells in culture . Cyclobutyl dimers between adjacent pyrimidine bases, the major photochemical lesions for these effects in prokaryotes, also play a part in UVR effects on eukaryote cells . Pyrimidine dimers have been isolated from in vivo UV-irradiated guinea pig and mouse skin . The wavelength dependence for dimer induction is similar to that for acute skin reactions but no direct causal relationship has been established . Sunlight UVA may induce dimers in skin DNA . Excision of dimers from mouse skin in vivo is deficient as it is for most rodent cells in culture; human cell excision is efficient and the difficulties in interpretation of UV-carcinogenesis results with mice in terms of human skin cancer are therefore, increased.

Arch Virol, 1978, 56(1-2), 15 - 31
Preparation of projection-less particles from influenza virus and their messenger activities in prokaryotic and eukaryotic systems; Arida EN et al.; A fraction of projection-less particles was prepared from influenza A/Dunedin/4/73 and A/Victoria/3/75 (X-47) (H3N2) by detergent treatment and extraction into ether at 0 degrees C . The activity of this material in stimulating protein synthesis in vitro was studied and compared with that of isolated virion RNA using a) an RNA-dependent E . coli system, and b) a wheat germ system . In the bacterial system the purified RNA had the highest template activity, while in the eukaryotic system the disrupted particle preparation was by far the most active . Translation products were formed with immunological and electrophoretic properties similar to those of several influenza virion proteins . The experiments indicate that, when added in the form of disrupted projection-less particles, RNA from influenza A2 virus is utilized as a template by eukaryotic ribosomes.

Proc Natl Acad Sci U S A, 1978 Jan, 75(1), 361 - 5
Detection of prokaryotic signal peptidase in an Escherichia coli membrane fraction: endoproteolytic cleavage of nascent f1 pre-coat protein; Chang CN et al.; An inverted membrane vesicle fraction isolated from uninfected Escherichia coli and largely derived from the inner membrane has been shown to contain an endoproteolytic activity that cleaves nascent bacteriophage f1 pre-coat protein into two identifiable products . The electrophoretic mobility on sodium dodecyl sulfate/urea/polyacrylamide gels and the partial amino-terminal sequence of the larger fragment were indistinguishable from those of the mature phage coat protein . Partial amino-terminal sequence analysis showed that the smaller fragment corresponds to the amino-terminal "signal peptide" of f1 pre-coat protein . Cleavage occurred only if the membrane fraction was present during in vitro synthesis, and was not observed if it was added after completion of pre-coat protein synthesis . The cleavage reaction was strongly stimulated when the membrane fraction was present together with the nonionic detergent Nikkol . These results are consistent with and discussed in terms of the signal hyothesis.

J Biol Chem, 1977 Dec 25, 252(24), 9032 - 42
Studies of low molecular weight RNA from cells infected with adenovirus 2 . I . The sequences at the 3' end of VA-RNA I; Celma ML et al.; VA-RNA I is a low molecular weight RNA produced in large amounts in cells infected with adenoviruses . The 3' terminus of this RNA may represent a transcription termination site . We have demonstrated that this RNA occurs in infected cells in several forms which differ in the number of uridylic acid residues at the 3' ends . The nucleotide sequence of a DNA fragment overlapping the 3' end of VA-RNA I has been determined . The DNA could encode up to 4 uridylic acid residues at the 3' end of the RNA . The DNA sequence shows some similarity to known transcription termination sequences in prokaryotic systems.

J Biol Chem, 1977 Dec 25, 252(24), 9047 - 54
Studies of low molecular weight RNA from cells infected with adenovirus 2 . III . The sequence of the promoter for VA-RNA I; Pan J et al.; VA-RNA I is one of the very few RNA species produced in animal cells whose transcriptional initiation site is known precisely . We have analyzed the nucleotide sequence of the DNA preceding the 5' end of VA-RNA I and compared it with known prokaryotic promoters and presumptive eukaryotic promoters.

Z Naturforsch {C}, 1977 Nov-Dec, 32(11-12), 954 - 6
Characterization of a soluble NADH-independent nitrate reductase from the photosynthetic bacterium Rhodopseudomonas capsulata; Alef K et al.; The assimilatory nitrate reductase was purified 60-fold from a newly isolated, nitrate assmilating strain of the photosynthetic bacterium Rhodopseudomonas capsulata . The enzyme had a molecular weight of about 180 000 dalton and was typically prokaryotic in that it was not active with reduced pyridine nucleotides but rather with reduced flavins.

J Exp Med, 1977 Nov 1, 146(5), 1182 - 94
Type I Escherichia coli pili: characterization of binding to monkey kidney cells; Salit IE et al.; We have demonstrated binding of purified pili from a strain of Escherichia coli to Vero cell monolayers as a model of prokaryotic-eukaryotic cell adherence . Pili bound to the tissue culture in a rapid reaction that did not require enzymatic activation . Attachment occurred optimally at pH 4-5 and could be inhibited by analogues of D-mannose, anti-pili antibodies, or by preincubation of tissue cells with mannose-specific plant lectins . Binding remained after treatment of the monolayer with glycosidases, trypsin, or a protease mixture but was enhanced after neuraminidase treatment . These results indicate that bacterial binding can occur via pili which act like lectins and presumably bind to mannose-containing glycoproteins on mammalian cell surfaces.

Nature, 1977 Oct 20, 269(5630), 655 - 61
Recent excitement in the DNA replication problem; Alberts B et al.; It is now possible to reproduce most of the reactions involved in DNA replication using prokaryotic enzymes in vitro . Such systems have revealed that DNA replication is a complex process depending on a relatively large number of proteins, and that nucleoside triphosphate hydrolysis energy is used at several discrete steps . Much of the complexity of DNA replication may arise from the need for extreme copying fidelity.

Nucleic Acids Res, 1977 Oct, 4(10), 3655 - 63
Sequence of the 3'-terminal 21 nucleotides of yeast 17S ribosomal RNA; De Jonge P et al.; The sequence of the 3'-terminal 21 nucleotides of 17S ribosomal RNA from the yeast Saccharomyces carlsbergensis has been determined to be (Y)G-m62A-m62A-C-U-C-G-C-G-G-A-A-G-G-A-U-C-A-U-U-AOH . This sequence shows extensive homology with the 3'-terminal sequence of 16S rRNA from Escherichia coli including the presence of the two adjacent N6-,N6-dimethyladenosines observed in the small subunit rRNA of eukaryotes as well as of many prokaryotes.

Proc Natl Acad Sci U S A, 1977 Oct, 74(10), 4401 - 5
Computer analysis of nucleic acid regulatory sequences; Korn LJ et al.; We describe a computer program designed to facilitate the analysis of nucleic acid sequences . The program can search several nucleic acid sequences for oligonucleotides common to all of them . It can examine a DNA or RNA sequence for two kinds of homologous regions--repetitions and dyad symmetries . The homologies need not be perfect: mismatches and "looping out" of nucleotides are allowed . The program also finds (A+T)- and (G+C)-rich regions, locates restriction enzyme recognition sites, determines the distribution of di- and trinucleotides, and performs various other functions . We include two representative applications of the program . All published prokaryotic transcription termination sequences (June 1977) were found to share the following features: (i) a string of at least five T residues, (ii) the sequence CGGGC or a close analog immediately preceding the T cluster, (iii) a region of strong dyad symmetry preceding the Ts and including the CGGGC sequence . A sequence of 221 nucleotides consisting of the Escherichia coli trp promoter, operator, and leader was found to contain two strong dyad symmetries . These homologies both occur at known regulatory sites; no comparable homologies occur in regions without regulatory significance.

Proc Natl Acad Sci U S A, 1977 Sep, 74(9), 4041 - 5
Extraction of an actin-like protein from the prokaryote Mycoplasma pneumoniae; Neimark HC; An actin-like protein has been identified in cell extracts from the prokaryote Mycoplasma pneumoniae . This protein bears a striking resemblance to actin from vertebrates: (i) the solubility of the protein during isolation is analogous to that of actin bound to myosin (soluble in high ionic strength salt solution and insoluble at low ionic strength), (ii) sodium dodecyl sulfate treatment of the partially purified M . pneumoniae extract produces a protein with an electrophoretic mobility very close to that of vertebrate actin in sodium dodecyl sulfate/polyacrylamide gels, (iii) treatment of preparations with ATP-Mg2+ allows separation of long curvilinear filaments, 5-6 nm wide, that closely resemble eukaryotic filamentous actin, and (iv) the prokaryotic filamentous actin binds vertebrate heavy meromyosin fragments to form hybrid compleexes with the characteristic shape of periodic repeating arrowheads, and no heavy meromyosin is bound in the presence of ATP.

Biokhimiia, 1977 Aug, 42(8), 1347 - 60
{Mitochondrial ribosomes}; Odintsova MS et al.; Some present-day conceptions on the structure and physiochemical and functional properties of mitochondrial ribosomes of higher and lower eukaryotes are reviewed . Mitochondrial ribosomes are compared to the ribosomes of prokaryotic and eukaryotic types and plastid ribosomes; biogenesis and functions of mitochondrial ribosomes are also discussed.

Orig Life, 1977 Aug, 8(2), 155 - 68
The colonial rock-forming microfossils of the Bohemian Upper Proterozoic (Czechoslovakia), 'Bohemipora Pragensis' n.g., n.sp; Pacltova B; Large amounts of well preserved microfossils have been reported from the cherts of the Upper Proterozoic of the Bohemian Massif (Middle Europe) . They resemble those described by Cayeux (1894) from the Upper Proterozoic (Brioverian) of Bretagne (France) . It is shown, unlike the views of Cayeux and his followers (Deflandre, 1955, and Graindor 1957), that the observed structures did not belong to individuals but to colonies of filamentous prokaryotic organisms, most probably blue-green algae (Cyanophyta) . These produced specific crystal-like mineral aggregation round each filament . Scanning microscope examination has revealed that the individual facets of these mineral crystals were perforated by the openings through which the thread-like bodies of these primitive organisms protruded . It is shown that these microorganisms were attached to the cells of other, bigger microorganisms and enveloped them . Some of these substrate organisms might have been eukaryotic algae . The thecae gradually accumulated around the cells of these carrier organisms and after death the colonies disintegrated to constitute the main component of the sediment . The microfossils described are just a major component of a complicated fossil assemblage comprising coccoid and filamentous blue-green algae and bacteria . There are indications that several eukaryotic species might also have been present.

Can J Microbiol, 1977 Aug, 23(8), 1096 - 108
Fimbriation in gliding bacteria; MacRae TH et al.; Of twenty-two strains of gliding prokaryotes examined, all but three were found to possess polar fimbriae . Fimbriae were not observed on two gliders, while Chloroflexus aurantiacus bore abundant peritrichous fimbriae . In some gliding bacteria, fimbriae were associated with 'holes' surrounded by an electron-transparent collar bearing 12 spike-like projections.

Nucleic Acids Res, 1977 Aug, 4(8), 2831 - 41
A comparison of transcriptional linkage of tRNA cistrons in yeast and E . coli by the ultraviolet light technique; Feldman H; The ultraviolet light mapping technique was employed to determine the lengths of tRNA cistrons in yeast . The applicability of the method was first tested in the E . coli system, in which the mapping positions for some tRNA cistrons and the ribosomal 5S RNA genes as well as the existence of multimeric transcription units for tRNAs are known . Rates of the synthesis of the tRNAs and small rRNAs after irradiation with various doses of UV light were determined by pulse labeling and quantitation of the RNA species after twodimensional gel electrophoreses . The small ribosomal RNAs served for internal calibration in the estimtion of the target sizes . Our results suggest that--in contrast to the prokaryotic system--in yeast the majority of the tRNA genes are not linked into transcriptional units.

Nature, 1977 Jul 14, 268(5616), 109 - 15
Transposable genetic elements as agents of gene instability and chromosomal rearrangements; Nevers P et al.; Transposable genetic elements in prokaryotes and eukaryotes, when inserted at a given locus, can control expression of the locus and cause large scale rearrangements of adjacent DNA sequences . Striking similarities in genetic behaviour between the two groups of elements have led to the proposal of a molecular model of eukaryotic controlling elements, and to suggestions about the part such elements may play in evolution and differentiation.

Tsitologiia, 1977 Jul, 19(7), 711 - 24
{Role of the membranes in the regulation of the activity of genetic structures of bacteria and mitochondria}; Kazakova TB; The literature on DNA interaction with both the prokaryotic cell membranes and the mitochondria of the Eukaryota is surveyed . Data are presented in favour of membrane localization of DNA and of the regulatory role of membranes in genome expression . A possible "conformational" mechanism of the control of gene activity by conformational changes of membranes related to cell metabolism is discussed . The problems of protein-nucleic recognition are concerned.

Mikrobiologiia, 1977 Jul-Aug, 46(4), 676 - 82
{Membrane composition of Actinomyces hygroscopicus in the course of growth and development}; Efimova TP et al.; The membranes of actinomycetes do not differ from the membranes of other prokaryotes in the content of lipids, proteins, carbohydrates, and RNA, Lipids are represented mainly by phospholipids, particularly by phosphatidyl ethanolamine, cardiolipine, and phosphatidyl glycerol . The fatty acid composition of phospholipids does not change in the course of growth, and is represented by 80 per cent with branched fatty acids having 15-17 carbon atoms . Over 20 fractions are found in proteins isolated from the membranes of actinomycetes grown for 1-3 days and studied by means of electrophoresis in polyacrylamide gel, and only 7-8 fractions, in the membranes of actinomycetes cultivated during 5-7 days.

Proc Natl Acad Sci U S A, 1977 Jul, 74(7), 2973 - 5
Genetic instability in Drosophila melanogaster: putative multiple insertion mutants at the singed bristle locus; Golubovsky MD et al.; A series of eleven independent mutants at the X chromosome singed bristle (sn) locus of Drosophila melanogaster is described . All mutants descend from flies caught in the wild and bred in the laboratory . On the basis of their inordinately high spontaneous mutation frequency, ten of the mutants are classified as putative insertion mutants . Reversions to wild type occur at frequencies of 10(-4)-10(-3) . Some reversions appear to be losses of the inserted element, others appear (by analogy with prokaryotes) to be changes in the orientation of the inserted elements . Consistent with the insertion hypothesis, some sn mutants generate what are interpreted to be deletions at the sn locus . In their mutational properties, the sn mutants are analogous to insertion sequence (IS) elements and bacteriophage Mu of Escherichia coli, but the precise nature of the insertion remains unknown.

Naturwissenschaften, 1977 Jul, 64(7), 366 - 70
{Biosynthesis and structure of the yeast fatty acid synthetase complex}; Schweizer E; Genetic as well as biochemical data suggest that the yeast fatty-acid synthetase complex has an (AB)6 protein structure where A and B represent multifunctional polypeptide chains with molecular weights of 185000 and 180000 daltons, respectively . Subunit A contains at least 3 and subunit B4 of the 8 known biochemical functions of the multienzyme complex . It is concluded that this complex structure has evolved from the corresponding prokaryotic system of monofunctional enzymes due to a selective advantage regarding the biosynthesis and assembly of the complex components.

Eur J Biochem, 1977 Jul 1, 77(1), 69 - 75
The involvement of a complex between formylmethionyl-tRNA and initiation factor IF-2 in prokaryotic initiation; van der Hofstad GA et al.; A complex between initiation factor IF-2 and fMet-tRNA can be formed under ionic conditions, which are optimal for initiation complex formation . The complex can be retained on cellulose nitrate filters after fixing with glutaraldehyde . The IF-2 - FMet-tRNA complex formation is not influenced by GTP and GDP . Other nucleoside di of triphosphates also have no effect . Evidence is presented that this complex acts as an intermediate in polypeptide chain initiation . The IF-2 - fMet-tRNA complex formation is not influenced by initiation factors IF-1 and IF-3 . The binary complex can be bound to the 30-S subunit in the absence of GTP, which indicates that there is no concomittant binding of the IF-2 - fMet-tRNA complex and the nucleotide moiety to the 30-S subunit . The binding of the binary complex is stimulated by GTP . The influence of some inhibitors of initiation on the IF-2 - fMet-tRNA complex formation has been tested . Aurin tricarboxylic acid appeared to be a strong inhibitor, whereas the sulfhydryl reagents N-ethylmaleimide and p-chloromercuribenzoate had no effect.

Proc Natl Acad Sci U S A, 1977 Jul, 74(7), 2706 - 9
Escherichia coli 5S RNA binding proteins L18 and L25 interact with 5.8S RNA but not with 5S RNA from yeast ribosomes; Wrede P et al.; Reconstitution experiments showed that the two Escherichia coli 5S RNA binding proteins L18 and L25 form a specific complex with yeast 5.8S RNA and not with yeast 5S RNA . The yeast 5.8S RNA-E . coli protein complex was found to exhibit ATPase and GTPase activities that had previously been observed for the E . coli 5S RNA-protein complex . The tetranucleotide UpUpCpG, which is an analog of the tRNA fragment TpsipCpG, interacted strongly with 5S RNA-protein complexes from E . coli and Bacillus stearothermophilus and weakly with yeast 5.8S RNA . UpUpCpG did not bind to E . coli, B . stearothermophilus, or yeast 5S RNA or to the yeast 5.8S RNA-E . coli protein complex . It is suggested that 5.8S RNA evolved from prokaryotic 5S RNA and that the latter two RNAs are related and have similar functions in protein synthesis.

J Biol Chem, 1977 Jun 10, 252(11), 3952 - 60
Precursors of ribosomal RNA in the cellular slime mold Dictyostelium discoideum . Isolation and characterization; Batts-Young B et al.; The pathway of ribosomal RNA biogenesis in Dictyostelium discoideum has been defined through identification, isolation, and characterization of the rapidly labeled nuclear RNAs which are intermediates in the process . Comparison of the methylation patterns, base compositions, two-dimensional oligonucleotide maps, and hybridization properties of these intermediate RNAs with those of mature rRNAs has established clearly the precursor-product sequence relationships supporting the following scheme for rRNA production and processing: (formula: see text) The relationship of the 37 S RNA of Dictyostelium to primary rRNA transcripts of prokaryotes and other eukaryotes is discussed.

Biosystems, 1977 Jun, 9(1), 35 - 42
Symbiosis and the evolution of prokaryotes; King GA; It is postulated, with support from kinetic modelling, that a succession of symbioses was the major process of evolution during the early stages of life . The process became less effective with the passage of time, while evolution by the natural selection of variants became more effective . The postulate may contribute usefully to discussions on the evolution of biochemical complexity and the structure of cells.

Chromosoma, 1977 Apr 20, 60(4), 297 - 344
The diminution of Heterochromatic chromosomal segments in Cyclops (Crustacea, Copepoda); Beermann S; The chromosomes of Cyclops divulsus, C . furcifer, and C . strenuus, like those of several other Copepods, undergo a striking diminution of chromatin early in embryogenesis . The process is restricted to the presumptive soma cells and occurs at the 5th cleavage in C . divulsus, at the 6th and 7th in C . furcifer, and at the 4th in C . strenus . The eliminated chromatin derives from the excision of heterochromatic chromosome segments (H-segments) . Their chromosomal location is different in the three investigated species: Whereas in C . divulsus and C . furcifer the H-segments form large blocks-exclusively terminal in the former and terminal as well as kinetochoric in the latter-the germ line heterochromatin in C . strenuus is scattered all along the chromosomes . Extensive polymorphism exists with respect to the length of the terminal H-segments in C . furcifer, and with respect to the overall content of heterochromatin in the chromosomes of C . strenuus . In a local race of C . strenuus an extreme form of dimorphism has been found which is sex limited: females as a fule are heterozygous for an entire set of large (heterochromatin-rich), and a second set of small chromosomes in their germ line . Males are homozygous for the large set . In the first three cleavage divisions the H-polymorphism is solely expressed through differences of chromosome length . Following diminution the differences between homologous have disappeared . Feulgen cytophotometry demonstrates that in the three species the 1C DNA value for the germ line, as measured in sperm, is about twice that measured in somatic mitoses (germ line/soma C-values in picograms of DNA: C . strenuus 2.2/0.9, C . furcifer 2.9/1.44, C . divulsus 3.1/1.8) . - The data imply that chromatin diminution is based on a mechanism which allows specific DNA segments, regardless of their location and size, to be cut out from the chromosomes without affecting the structural continuity of the remaining DNA . The mechanism may be analogous to that of prokaryotic DNA excision.

Orig Life, 1977 Apr, 8(1), 39 - 53
Symbiosis and the origin of life; King GA; The paper uses chemical kinetic arguments and illustrations by computer modelling to discuss the origin and evolution of life . Complex self-reproducing chemical systems cannot arise spontaneously, whereas simple auto-catalytic systems can, especially in an irradiated aqueous medium . Self-reproducing chemical particles of any complexity, in an appropriate environment, have a self-regulating property which permits long-term survival . However, loss of materials from the environment can lead to continuing decay which is circumvented by physical union between different kinds of self-reproducing particles . The increasing complexity produced by such unions (symbioses) is irreversible so that the chemical system evolves . It is suggested that evolution by successive symbioses brought about the change from simple, spontaneously arising, auto-catalytic particles to complex prokaryotic cells.

Biokhimiia, 1977 Apr, 42(4), 598 - 608
{Fractionation and purification of DNA methylases and specific endonucleases from cells of Escherichia coli SK}; Nikol'skaia II et al.; Fractionation and purification of DNA methylases and specific endonucleases from E . coli SK responsible for DNA specificity to host prokaryotic cells were studied . The most efficient purification was achieved by precipitation of proteins by 0.6 saturated ammonium sulfate with subsequent chromatography on KM-cellulose and concentration of fractions by dialysis against glycerol . Under these conditions the methylase activity produced 4 discrete fractions . Due to purification the specific activity of methylases increased 11--20-fold in various fractions . Methylase from the first (A) and fourth (BII) peaks catalyzed the methylation of cytosine to produce 5-methylcytosine; methylase from the third peak (BI) methylated adenine to produce 6-methylaminopurine . The chemical specificity of the second peak (B) methylase could not be established due to very high lability of the enzyme in this fraction . Specific endonuclease was found in the gradient zones eluted by 0.1--0.2 M and 0.65--0.75 M NaCl . It is assumed that those enzymes providing for DNA hydrolysis up to the formation of high--molecular discrete fragments, are restricting endonucleases of the SK system . The results obtained strongly suggest the existence of several types of methylases and restricting endonucleases in E . coli SK cells.

Biochim Biophys Acta, 1977 Mar 25, 486(3), 451 - 61
Quantitative effects of unsaturated fatty acids in microbial mutants . VII . Influence of the acetylenic bond location on the effectiveness of acyl chains; Lands WE et al.; The ability of a series of 18 carbon acetylenic fatty acids to fulfill the unsaturated fatty acid requirements of Escherichia coli and Saccharomyces cerevisiae was investigated . Despite their high melting points (greater than 40 degrees C), several isomers of the acetylenic fatty acids were as efficient or more efficient in supporting growth than the analogous fatty acid having a cis-double bond . The efficiencies of the different positional isomers in supporting cell proliferation varied from essentially 0 cells per fmol for the 2-5 and 13-17 isomers to high values when the acetylenic bond was near the center of the chain: e.g . 45 E . coli and 5.5 S . cerevisiae cells/fmol for the 10 isomer . A striking ineffectiveness of the 9 isomer was observed with E . coli . The 7, 8 and 10 isomers were at least 10-fold more efficient than any of the other positional isomers in supporting the growth of E . coli . In contrast, the 9 isomer was among the most effective acetylenic fatty acids tested with the yeast mutant . Chromatographic analysis of the extracted lipids indicated that each of the acetylenic isomers tested (except delta2 and delta3) could be esterified by the prokaryotic and eukaryotic microorganisms . The content of unsaturated plus cyclopropane acids observed when growth ceased in E . coli cultures supplemented with growth-limiting concentrations of the acetylenic fatty acids ranged from approx . 15 mol% for the 8 isomer to approx . 35 mol% for the 14 and 17 isomers . The 8-11 isomers were observed to be esterified predominantly at the two position in phosphatidylethanolamine of E . coli and in phosphatidylcholine of S . cerevisiae.

J Biol Chem, 1977 Mar 25, 252(6), 1873 - 80
DNA polymerases from bakers' yeast; Chang LM; Two DNA polymerases are present in extracts of commercial bakers' yeast and wild type Saccharomyces cerevisiae grown aerobically to late log phase . Yeast DNA polymerase I and yeast DNA polymerase II can be separated by DEAE-cellulose, hydroxylapatite, and denatured DNA-cellulose chromatography from the postmitochondrial supernatants of yeast lysates . The yeast polymerases are both of high molecular weight (greater than 100,000) but are clearly separate species by the lack of immunological cross-reactivity . Analysis of associated enzyme activities and other reaction properties of yeast DNA polymerases provides additional evidence for distinguishing the two species . Enzyme I has no associated nuclease activity but does carry out pyrophosphate exchange and pyrophosphorolysis reactions, and has an associated 3'-exonuclease activity . Enzyme I does not degrade deoxynucleoside triphosphates and cannot utilize a mismatched template . Enzyme II does carry out a template-dependent deoxynucleoside triphosphate degradation reaction and can excise mismatched 3'-nucleotides from suitable template systems . Earlier studies have shown that both Enzyme I and Enzyme II are inhibited by N-ethylmaleimide . The yeast enzymes are not identical to any known eukaryotic or prokaryotic DNA polymerases . In general, Enzyme I appears to be most similar to eukaryotic DNA polymerase alpha and Ezyme II exhibits properties of prokaryotic DNA polymerases II and III.

Philos Trans R Soc Lond B Biol Sci, 1977 Mar 21, 277(955), 201 - 26
The time and duration of meiosis; Bennett MD; Ever since meiosis was recognized as a process there has been a continuing interest in its temporal aspects . Two main types of meiotic timing experiments have been conducted: first, experiments to estimate the duration of meiosis (and sometimes its stages); second, experiments to locate the sensitive stage(s) when exposure of meiocytes to various treatments can affect meiotic chromosome behaviour (e.g . pairing or recombination) . Such experiments have played an important role in increasing our understanding of the meiotic process . The duration of meiosis has been estimated in about 70 organisms, including two prokaryotes (yeast and Chlamydomonas) and the following eukaryotes: 1 Basidiomycete (Coprinus lagopus), 2 Gymnosperms (Larix decidua and Thuja plicata gracilis) . at least 39 angiosperms, and at least 26 animal species . The duration of female meiosis has been estimated in far fewer species than male meiosis . However, estimates of the duration of female meiosis are available for 6 angiosperms . Drosophila melanogaster, Xenopus laevis, and several mammals . Comparison of these data shows that the duration of meiosis is one of the most variable aspects of the meiotic process, ranging from less than 6 h in yeast to more than 40 years in the human female . Developmental holds at different stages of meiosis are common in plants and animals, and inevitably prolong the meiotic division . However, even among species without developmental holds, the duration of meiosis is very variable . For instance, in animals it ranges from about 1-2 days in male Drosophila melanogaster to more than 24 days in male Homo sapiens and several Orthopterans . Despite the large variation in the duration of meiosis three generalizations can be made: (i) first prophase is always very long compared with the remaining meiotic stages, (ii) the rate of meiotic development is very slow compared with the rate of development in dividing somatic meristem cells of the same organisms under the same conditions, (iii) the duration of meiosis is characteristic of the genotype and species . Four main factors have been recognized which effect or determine the duration of meiosis, namely (1) environmental factors (e.g . temperature); (2) nuclear DNA content; (3) ploidy level of the organism; and, (4) the genotype . Because nuclear DNA content plays a major role in determining the duration of meiosis, it has been suggested that DNA influences the rate of meiotic development in two ways: first through its informational content (the genotype), and second indirectly by the physical and mechanical effects of its mass independently of its informational content (i.e . the nucleotype) . Thus, the observed duration of meiosis is the result of a complex genotype-nucleotype-environment interaction . With the obvious exception of variation caused by developmental holds, changes in the duration of meiosis usually involve proportional changes in the durations of all its stages...

Chromosoma, 1977 Mar 7, 60(1), 39 - 47
The structure of mesokaryote chromosome; Hamkalo BA et al.; Condensed and dispersed forms of the chromosomes of the dinoflagellate, Prorocentrum micans, deposited on grids by the microcentrifugation technique were studied by electron microscopy . In the normally condensed form, the chromosomes appear as banded rods surrounded by a peripheral cloud of partially dispersed fibers . Single fibers in these and in extensively dispersed preparations appear as smooth threads of uniform diameter (55-65 A) . The chromosome fibers are contrasted by positive-group-specific stains indicating the presence of cationic moieties associated with the DNA . Occasionally Y-shaped chromosomes are seen; these may be replicating structures . These observations are in general agreement with studies of dinoflagellate chromosomes by other techniques, and provide support for the suggestion that these organisms possess a genome organization whose structure is typical of neither prokaryotes nor eukaryotes, and hence may be intermediate forms.

Nucleic Acids Res, 1977 Mar, 4(3), 663 - 71
Wheat embryo mitochondrial 18S ribosomal RNA: evidence for its prokaryotic nature; Bonen L et al.; We present a catalog of sequences of oligonucleotides produced by T1 ribonuclease digestion of 32P-labeled small-ribosomal-subunit RNA ("18S rRNA) isolated from purified wheat embryo mitochondria . This catalog is compared to catalogs published for prokaryotic and chloroplast 16S rRNAs and to preliminary results for wheat cytosol 18S rRNA . These comparisons indicate that: (1) wheat mitochondrial 18S rRNA is clearly prokaryotic in nature, showing significantly more sequence homology with 16S rRNAs than can be expected to arise by chance (p less than 0.000001); (2) shared oligonucleotide sequences include an especially high proportion of those identified as conserved in the evolution of prokaryotic rRNAs; and (3) wheat embryo mitochondrial and cytosol 18S rRNAs retain no more, and perhaps less, than the minimum sequence homology detectable by this sensitive method . These results argue in favor of an endosymbiotic origin for mitochondria.

Eur J Biochem, 1977 Mar 1, 73(2), 607 - 15
{Methionyl-tRNA synthetase from wheat embryo: dissociation into subunits (author's transl)}; Chazal P et al.; Wheat -embryo methionyl-tRNA synthetase is a dimeric protein of beta2 structure . When highly diluted, it loses the capacity to catalyze ATP-{32P}PPi exchange and to aminoacylate tRNAMet: at low enzymatic concentrations the rates of formation of{32P}ATP and {14C}methionyl-tRNAMet are lower than those predicatedby extrapolating the rates determined at higher enzyme concentrations . The difference between observed and expected rates becomes greater with decreasing enzyme concentration . Filtration of purified, dilute enzyme preparations on Sephadex G-200 results in the separation of dimer and monomer fractions . The proportion of monomer present increases with increasing pre-incubation times before the assay and demonstrates an equilibrium between active dimers and being shifted towards the production of monomers . Datapreviously gathered for Escherichia coli prolyl-tRNA synthetase and for bovine-pancreatic tryptophanyl-tRNA synthetase, coupled with the present results, suggests that the dissociation of dimeric synthetases may be a general phenomenon in eukaryotes as well as in prokaryotes . The number of sub-units and the dissociation constant were obtained at equilibrium, according to relations adapted to the case of oligomeric enzymes (KD congruent to 13 nM at 25 degrees C and pH 7.5) . Rate constants were determined by kinetic studies of the attainment of equilibrium . The rate constant k1 for monomolecular dissociation was determined to be 1.85- 10-3 s-1 and k2 for the bimolecular association to be 0.145 - 106 M-1 s-1 . The KD calculated from k1 and k2 was coherent with the experimentally determined value, at equilibrium . The sub-unit interactions, which involve only a small quantity of energy (delta G degree congruent to + 11 kcal mol-1; +45 kJ mol-1) at 25 degrees C, depend on the ionic environment of the medium and the presence of substrates . Alkaline pH favors monomer production, while the presence of methionine, (Mg-ATP)2- and tRNAMet protect the synthetase from dissociation . 2-mercaptoethanol and dithioerythritol prevent only slightly the loss of activity . Bovine serum albumin, however, protects the enzyme from dissociation under dilute conditions.

Mech Ageing Dev, 1977 Mar-Apr, 6(2), 143 - 52
Systems analysis of possible mechanisms of mammalian aging; Denckla WD; A comparison is made between how bacteria and men use their DNA to accomplish any major biological function . To make this comparison, a modified cybernetic analysis was used . This new type of cybernetic analysis makes a distinction between controlled and regulated systems and may permit an extension of cybernetics into new areas of biology . Prokaryotes have only regulated systems for all major functions, whereas eukaryotes can have both regulated and controlled systems . Several lines of reasoning, including the new cybernetic analysis, suggest that death, as opposed to aging, may be a regulated function in mammals . By analogy with other major regulated developmental functions in mammals, it is also suggested that the hypothalamic-pituitary axis may be the site for the regulation of the time of death . An example of how the pituitary might act on the DNA of peripheral cells to cause possible, severe loss of functional capacity is given by some recent experiments with RNA polymerase activity of liver nuclei from rats of different ages and with different endocrine states.

Mol Cell Endocrinol, 1977 Mar, 7(1), 89 - 100
Binding characteristics of L-triiodothyronine to isolated rat liver chromatin; Yoshizato K et al.; The binding characteristics of {125I}-labeled L-triiodothyronine (T3) to chromatin isolated from rat liver nuclei were investigated . Binding of T3 to chromatin showed temperature-, incubation time-, and DNA concentration-dependence . According to Scatchard analysis, the apparent equilibrium dissociation constant was 225 pM, with a maximum binding capacity of about 0.2 pmoles per mg DNA . Displacement studies with unlabeled thyroxine (T4) and T3 showed that the binding sites for T4 might be the same as T3 but the binding affinity of the former was less than that of the latter . The binding was completely inhibited by the eukaryotic RNA polymerase inhibitor, rifampicin AF/021, but not by the prokaryotic inhibitor, rifampicin and alpha-amanitin . These observations indicate that the receptors for T3 have certain properties in common with RNA polymerase or other enzyme proteins which are sensitive to the rifampicin derivative . The hormone--chromatin fragments complex was solubilized from residual chromatin by digestion with DNase, but not with RNase, suggesting that the T3 receptors localize in the DNase-sensitive regions of DNA in the chromatin . This provides a useful method to use to investigate the localization of the receptor proteins in the chromatin and the interaction of the hormone-receptor complex with DNA.

Biochemistry, 1977 Feb 22, 16(4), 766 - 76
Initial position of aminoacylation of individual Escherichia coli, yeast, and calf liver transfer RNAs; Chinault AC et al.; Transfer RNAs from Escherichia coli, yeast (Sacharomyces cerevisiae), and calf liver were subjected to controlled hydrolysis with venom exonuclease to remove 3'-terminal nucleotides, and then reconstructed successively with cytosine triphosphate (CTP) and 2'- or 3'-deoxyadenosine 5'-triphosphate in the presence of yeast CTP(ATP):tRNA nucleotidyltransferase . The modified tRNAs were purified by chromatography on DBAE-cellulose or acetylated DBAE-cellulose and then utilized in tRNA aminoacylation experiments in the presence of the homologous aminoacyl-tRNA synthetase activities . The E . coli, yeast, and calf liver aminoacyl-tRNA synthetases specific for alanine, glycine, histidine, lysine, serine, and threonine, as well as the E . coli and yeast prolyl-tRNA synthetases and the yeast glutaminyl-tRNA synthetase utilized only those homologous modified tRNAs terminating in 2'-deoxyadenosine (i.e., having an available 3'-OH group) . This is interpreted as evidence that these aminoacyl-tRNA synthetases normally aminoacylate their unmodified cognate tRNAs on the 3'-OH group . The aminoacyl-tRNA synthetases from all three sources specific argining, isoleucine, leucine, phenylalanine, and valine, as well as the E . coli and yeast enzymes specific for methionine and the E . coli glutamyl-tRNA synthetase, used as substrates exclusively those tRNAs terminating in 3'-deoxyadenosine . Certain aminoacyl-tRNA synthetases, including the E . coli, yeast, and calf liver asparagine and tyrosine activating enzymes, the E . coli and yeast cysteinyl-tRNA synthetases, and the aspartyl-tRNA synthetase from yeast, utilized both isomeric tRNAs as substrates, although generally not at the same rate . While the calf liver aspartyl- and cysteinyl-tRNA synthetases utilized only the corresponding modified tRNA species terminating in 2'-deoxyadenosine, the use of a more concentrated enzyme preparation might well result in aminoacylation of the isomeric species . The one tRNA for which positional specificity does seem to have changed during evolution is tryptophan, whose E . coli aminoacyl-tRNA synthetase utilized predominantly the cognate tRNA terminating in 3'-deoxyadenosine, while the corresponding yeast and calf liver enzymes were found to utilize predominantly the isomeric tRNAs terminating in 2'-deoxyadenosine . The data presented indicate that while there is considerable diversity in the initial position of aminoacylation of individual tRNA isoacceptors derived from a single source, positional specificity has generally been conserved during the evolution from a prokaryotic to mammalian organism.

Mol Cell Biochem, 1977 Feb 4, 14(1-3), 143 - 9
Gene expression in mitochondria and bacteria; Herrlich P et al.; Mitochondria and bacteria possess protein synthesizing machineries which are similar in many respects; The regulation of gene expression in mitochondria is unknown . We, therefore, tried to use a well-established prokaryotic regulatory system for the exploration of mitochondrial gene regulation . DNA of the bacterial virus can be used as a template for gene expression in a mitochondrial in vitro system . The gene directed enzyme synthesis in the mitochondrial system is the basis for a study of regulation in mitochondrial protein synthesis.

Biochim Biophys Acta, 1977 Feb 3, 474(3), 386 - 97
Discoordination of ribosomal RNA metabolism during metabolic shifts of Spirodela plants; Rosner A et al.; The effects of metabolic shifts on nucleic acid syntheses have been widely studied in prokaryotes, but not in plants because of a paucity of suitable systems . Spirodela (Duckweed) was thus used to ascertain the response of the nucleocytoplasmic (nc) and plastid ribosomal RNA metabolisms to partial and total carbon deprivation . The 0.56 X 10(6) Mr plastid rRNA is the one species of RNA most affected by metabolic shifts; unlike other species, its appearance is delayed by deprivation and it appears more rapidly than other species on transfer from dark to light . The data suggest a discoordination between the transcription and processing of plastid ribosomal precursors . Incorporation into all nc and plastid rRNAs was severely reduced and all rRNA precursors accumulated in green plants that were completely deprived of carbon by transferring to the dark, without sucrose . The amounts of nc and plastid precursors transcribed readjusted to the reduced amounts processed to mature RNA only after long periods in the dark with sucrose . This delay involved the formation of new colorless plants . Less plastid RNAs, compared to nc RNAs are found in the dark steady state.

Nucleic Acids Res, 1977 Feb, 4(2), 381 - 95
Stimulation of RNA polymerase I and II activities by 17 beta -estradiol receptor on chick liver chromatin; Dierks-Ventling C et al.; The endogenous transcriptional capacity (RNA polymerase I and II activity) of liver chromatin from chicks treated with 17 beta-estradiol for 24 h (E 24) was double that of the controls . E 24 chromatin contained estradiol receptor activity while control chromatin did not . Its presence suggested an implication in the enhanced activities of RNA polymerases of E 24 chromatin . When semi-purified estradiol receptor was added to control chromatin, the endogenous transcriptional capacity of this chromatin was greatly increased . Studies with alpha-amanitin showed that both RNA polymerase I and II were stimulated by the estradiol receptor . This stimulation was observed as long as homology of the system was maintained . Solubilized homologous RNA polymerases were stimulated much less by the hormone complex in the presence of heterologous DNA than with homologous chromatin . Prokaryotic RNA polymerase could not be stimulated by chick liver estradiol receptor in the presence of heterologous DNA.

J Cell Biol, 1977 Feb, 72(2), 470 - 81
Temporal programming of chloroplast and cytoplasmic ribosomal RNA transcription in the synchronous cell cycle of Chlamydomonas reinhardtii; Wilson R et al.; Approximately 90% of the Chlamydomonas reinhardtii chloroplast and cytoplasmic rRNAs was transcribed in the nuclear G1 phase, which occurred during the light period under an alternating light-dark synchronization regime of 12 h each . The remaining 10% of chloroplast and cytoplasmic rRNAs was transcribed from its respective DNAs in the dark period, in the midst of an apparent turnover of a transcription appeared to be prokaryotic in sophistication . The transcription was not interrupted during chloroplast DNA synthesis which occurred during the light period . However, transcription of the nuclear DNA was repressed severely during the nuclear S phase in the dark period . The patterns of incorporation of 32P into chloroplast and cytoplasmic rRNA species in the cell cycle were similar to those of the actual rRNA synthesis as measured optically . However, the quantity of 32P incorporation per unit amount of rRNA synthesized varied considerably during the cell cycle, increasing in all rRNA's during the dark period . 32P incorporation data obtained from continuous and pulse 32P-labeling experiments also revealed a turnover of a small amount of both cytoplasmic and chloroplast rRNAs at the end of the S phase . The 32P incorporation into cytoplasmic and chloroplast rRNAs was well matched temporally with the 32P incorporation into their corresponding ribosomes, indicating that the newly synthesized rRNA molecules are utilized without delay throughout the cell cycle in the assembly of ribosomes.

Proc Natl Acad Sci U S A, 1977 Feb, 74(2), 575 - 8
Identification of chlorophyll b in extracts of prokaryotic algae by fluorescence spectroscopy; Thorne SW et al.; Solvent extracts of three different prokaryotic algae from three species of didemnid ascidians contained pigments identified, on the basis of their fluorescence excitation (E)and fluorescence emission (F)spectral maxima (measured in nm) at 77K, as chlorophyll a (E 449, F 678) and chlorophyll b (E 478, F 658) . The release of algae on cutting or freezing Diplosoma virens was accompanied by a strong unidentified acid that converted these pigments to pheophytins . This unexpected finding provided further confirmation of the identity of the chlorophylls on the basis of the fluorescence spectra at 77K of pheophytin a (E 415, F 669) and pheophytin b (E 439, F 655) . There was no evidence for the presence of the fluorescent bilin pigments found in other prokaryotic blue-green algae . Chlorophyll a/b ratios ranged from 2.6 to 12.0 in algae from different ascidians . The photosynthetic membranes were not organized into appressed thylakoids or grana in the algae from any of the three species of ascidians . The relationship between these observations and those in higher eukaryotic organisms is discussed.

J Protozool, 1977 Feb, 24(1), 154 - 63
Anaerobiosis and symbiosis with bacteria in free-living ciliates; Fenchel T et al.; Marine, sediment-dwelling ciliates were examined for cytochrome oxidase activity by a cytochemical method and for fine structural details . Species of Plagiopylidae (Trichostomatida), i.e . Plagiopyla frontata, Sonderia vorax and Sonderia sp., and of Heterotrichda, i.e., Parablepharisma pellitum, Parablepharisma sp., Metopus contortus, Metopus vestitus and Caenomorpha capucina; previously considered to be obligate anaerobes because of their sulfide-containing habitat, do not have cytochrome oxidase activity or mitochondria with cristae or tubuli . The evolutionary origin and significance of anaerobic ciliates is discussed . Most of the anaerobic ciliates harbor a flora of ecto- and endosymbiotic bacteria as demonstrated by transmission and scanning electron micrographs . It is speculated that the bacteria may utilize the metabolic end products of the protozoa for growth and energy yielding processes . These associations are also compared with other, previously described cases of symbiosis involving prokaryotes and protozoa.

J Biol Chem, 1977 Jan 25, 252(2), 652 - 4
Antagonistic action between spermidine and putrescine on association and dissociation of purified, run-off ribosomes from Escherichia coli; Rosano CL et al.; The effects of polyamines on the equilibrium between prokaryotic ribosomal subunits and 70 S ribosomes have been studied as a function of concentration of Mg2+ from 2.5 to 7.5 mM . Run-off ribosomes were obtained from Escherichia coli and were washed with buffered 1 M NH4C1 . Spermidine at 1 mm favors association of subunits at all concentrations of Mg2+ . Putrescine, at concentrations above 8 mM, favors net dissociation at concentrations of Mg2+ below 4.5 mM . Streptomycin behaves like spermidine, while putrescine behaves like initiation factor 1 and initiation factor 3 . The effect of putrescine on dissociation is time-dependent and appears to have a half-life of about 3.5 min at 30 degrees . When added after the effects of spermidine or streptomycin on association have occurred, putrescine still causes dissociation . The data suggests that putrescine may reduce net formation of vacant 70 S ribosomes . Another possibility is that putrescine and spermidine may act antagonistically to maintain a labile equilibrium between ribosomal subunits and vacant 70 S ribosomes . It may be significant that the putrescine effect is observed at the concentration of Mg2+ found to be optimum for initiation.

J Cell Sci, 1977, 27, 81 - 90
Continuous DNA replication in the nucleus of the dinoflagellate Prorocentrum micans (Ehrenberg); Filfilan SA et al.; The uptake of tritiated thymine into cells of a heterogeneous population of Prorocentrum micans was investigated using light-microscope and electron-microscope autoradiography . Specificity of thymine uptake into DNA was demonstrated by the specific removal of label from wax-embedded material using DNase and by the high degree of localization of nuclear label to chromosomes in the electron-microscope autoradiographs . All nuclei, including both dividing and non-dividing cells, showed a substantial uptake of label, indicating that nuclear DNA synthesis in Prorocentrum micans is a continuous process . The level of DNA synthesis does show considerable variation, however, with very high levels in some interphase nuclei . The continuous replication of nuclear DNA provides further evidence of dinoflagellate affinity to the prokaryotes, and indicates that Prorocentrum micans is a very primitive eukaryote cell.

J Immunol Methods, 1977, 17(3-4), 241 - 7
A rapid micro method for the simultaneous determination of phagocytic-microbiocidal activity of human peripheral blood leukocytes in vitro; Smith DL et al.; A new, simple technique for simultaneously studying phagocytic and microbiocidal functions, using viable eukaryotic and prokaryotic microbes, is described . Fresh human venous blood from volunteers was placed on a coverglass and incubated to allow leukocyte adhesion to the coverglass . After clot removal, viable microbes in suspension were added and the coverglass preparation was incubated to allow phagocytosis . The excess microbes (E . coli, S . aureus, L . monocytogenes, and C . albicans each have been used) were then rinsed off, and the vital fluorochrome, acridine orange (AO), was used for staining . A wet mount was prepared and examined by reflected fluorescence with an ultraviolet microscope . Intact (viable) polymorphonuclear (PMN) leukocyte nuclei and microbes appeared green (orthochromatic) . Granules in the PMN cytoplasm were yellow or reddish . Nonviable PMN nuclei appeared yellowish or reddish and the nonviable microbes appeared bright red (metachromatic) . Thus, phagocytized microbes may be counted and identified as viable or non-viable.

Nucleic Acids Res, 1977 Jan, 4(1), 43 - 62
The interactions of the separated strands of satellite DNAs with other DNAs: 1 . Conditions for associations of the alpha-satellite of the guinea pig with heterologous double-stranded DNAs; Skinner DM et al.; The separated H- and L-strands of the alpha-satellite of the guinea pig, Cavea porcellus, recovered from centrifugation in alkaline CsC1 gradients, from complexes with 7 different double-stranded (ds) DNAs including those of 1 bacteriophage, 2 prokaryotes, 2 invertebrates and 2 mammals . The complexes are not artifacts due to in vitro labeling of the satellite, methods of collection, the presence of divalent cations, or the fact that trace amounts of single-stranded (ss) DNAs are used . More complex dsDNAs, such as that recovered from nicked RF M13, do not associate with dsDNAs.

Comp Biochem Physiol B, 1977, 58(1), 1 - 7
Evolution of ribosomal RNA; Ishikawa H; 1 . The G + C content of ribosomal RNA of animals seems correlated with the length of periods required for maturation of those organisms . 2 . In Protostomes of the animal kingdom, the size of the 28S rRNA molecule does not seem to correlate with the evolutionary stage of the organism . 3 . Aphids and water-fleas as well as some protozoa have the 18S rRNA with mol . wt of 0.9 x 10(6) against an overwhelming pressure of evolution to conserve the rRNA molecule of 0.7 x 10(6) daltons . 4 . All the Deuterostomes examined were distinguished from Protostomes by having the 28S rRNA's void of the hidden break at the central point . 5 . Aphids and nematodes are exceptional Protostomes in that they have the 28S rRNA's without the hidden break . This was discussed in the light of the evolutionary stage of these organisms . 6 . Molecular properties of chloroplast rRNA seem to evidence for endosymbiotic origin of this organelle . Mitochondrial rRNA differs considerably from prokaryotic rRNA with respect to molecular size and base composition.

Biochem Soc Symp, 1977, (42), 55 - 73
The deoxyribonucleic acid polymerases of non-vertebrate eukaryotes; McLennan AG et al.; DNA-dependent DNA polymerases have now been purified from a number of invertebrate animals, protists, higher plants and fungi . In this article we review the properties of these enzymes and compare them with the better-known enzymes of vertebrate animals and prokaryotes . Three facts emerge . Firstly, plants, protists and fungi contain high-molecular-weight DNA polymerases which may be capable of categorization into two groups on the basis of their properties in vitro . Secondly, no enzyme analogous to the vertebrate polymerase-beta has yet been found in such organisms, and thirdly, many of these enzymes possess associated exonuclease activities like those of the bacterial DNA polymerases . On the basis of these findings, some tentative proposals are made about the evolution of DNA polymerases.

Z Allg Mikrobiol, 1977, 17(3), 183 - 9
{Dependence of the specific growth rate of Escherichia coli MI 30 on the ammonia concentration}; Bergter F et al.; The transient behaviour of ammonium limited continuous cultures of E . coli ML 30 led to the hypothesis that the bistability of pyruvate formation primarily is caused by a bistability of the ammonia metabolism . Therefore, a function of mu({NH+4}) should be expected different from that of Monod type . Measurements of the specific growth rate during washout of continuous cultures at different ammonium concentrations and at such low cell concentrations that the changes in the ammonium concentration of the medium could be neglected, showed a complex function with a relative minimum near 2 mg/1NH+4 . This function allows bistability of the ammonium concentration in an ammonium limited continuous culture . The results are discussed on the basis of the two systems of ammonia assimilation found in prokaryotic cells.

Arzneimittelforschung, 1977 Jan, 27(1B), 190 - 9
{Gene expression in eucaryotic cells and its regulation (author's transl)}; Franke WW; Principles of 1 . the organisation and compartmentalisation of the eukaryotic nuclear genome and 2 . of the different processes involved in controlling its activity are outlined and the basic differences to prokaryotic cell systems are emphasized . The special composition and arrangement of the nuclear DNA of eukaryotes is demonstrated in terms of both redundancy classes (unique sequences, sequences of intermediate degrees of repetition, highly repetitive sequences, i.e., "simple sequences") and chromatin and chromosome organisation . The role of the nuclear envelope as an ubiquitous and characteristic structure involved in the compartmentalisation of the nuclear genome and its transcriptional machinery is illustrated . The diversity of the mechanisms of the controls of gene expression in the eukaryotic cells is discussed at different levels: a) chromatin elimination, b) polyploidisation, c) polytenisation, d) gene amplification, e) gene magnification, f) inactivation of genes by complexing with specific proteins and/or protamines, g) transcription, h) complex formation of transcriptional products with specific proteins, i) release of the transcriptional products from the template containing strands, j) processing of newly formed RNA's k) intranuclear degradation of newly formed RNA's, l) nucleocytoplasmic translocation, and m) various forms of RNA containing structures, including masked messenger RNA's and ribosome storages, in the cytoplasm . It is demonstrated that differences in transcriptional activity can be directly visualized and that a direct trnascriptional control of gene activity is indicated to exist at least in some specific cell systems.

Arzneimittelforschung, 1977 Jan, 27(1B), 182 - 5
{Genetic surgery: results of a new technique (author's transl)}; Hobom G; New techniques for cleaving DNA molecules at precisely defined points, and for successful DNA-transformation of E . coli have allowed genetic engineers to ligate DNA fragments of all possible origins and to convert them into replicating molecules sustained within bacterial cells . For this purpose, typically, segments of eukaryotic DNA are linked to bacterial "vectors", in particular plasmids carring their own replication machinery . This procedure allows to study the genetic organization of eukaryotic DNA and to detect whether or not the eukaryotic genes will function in a foreign environment . Work has just been initiated aiming at the complementary procedure, i.e., at introducing prokaryotic or foreign eukaryotic genes into eukaryotic cells which may carry hereditary defects.

Mol Gen Genet, 1976 Dec 31, 142(4), 317 - 31
Molecular weight distribution of ribosomal proteins from several vertebrate species; Martini OH et al.; Two-dimensional polyacrylamide gel electrophoresis of proteins from the separated ribosomal subunits of rabbit reticulocytes, rabbit liver, mouse liver, rat liver, chicken liver, and toad liver was performed using the "pH 4.5/SDS" system previously described (Martini and Gould, 1975), with internal standards to measure the molecular weight distributions . With few exceptions, the patterns were remarkably similar, indicating a high degree of conservation during evolution of both net charge (largely determining mobility in the first dimension) and size (determining mobility in the second dimension) . The aggregate mass (sum of molecular weights) of both small and large subunit proteins, about 0.65 X 10(6) and 0.95 X 10(6) daltons respectively, were invariant . These figures are significantly smaller than the hydrodynamically determined mass of protein in the subunits . The implications of this discrepancy, which is opposite that found in the prokaryotes, is discussed.

Biochim Biophys Acta, 1976 Dec 13, 454(3), 419 - 28
Polypyrimidine sequences found in eukaryotic DNA have been conserved during evolution; Straus NA et al.; L-cell DNA contains an unexpectedly large amount of long pyrimidine tracts . Hydroxyapatite chromatography has been employed to show that these polypyrimidines hydridize extensively to the reiterated DNA of a large number of eukaryotes but fail to hybridize to prokaryotic DNA . This reaction is sequence specific and not the result of a special property of polypyrimidines since random 3H-labelled poly(dC-dT) shows poor hybridization to eukaryotic DNA . The hybrids formed by L-cell polypyrimidines and heterologous repeated sequences have a higher thermal stability than the corresponding hybrids of total repeated DNA indicating that sequences related to these polypyrimidines have been conserved during evolution . Furthermore, at least some of these tracts are transcribed because they are capable of reacting extensively with total cellular RNA . Although the function of these sequences is not yet known, the fact that they are widely conserved in evolution and also transcribed leads us to speculate that they play an an important role in eukaryotic cells.

J Biol Chem, 1976 Dec 10, 251(23), 7380 - 7
Chromatin receptors for thyroid hormones . Interactions of the solubilized proteins with DNA; MacLeod KM et al.; Thyroid hormone-responsive tissues contain chromatin "receptor" proteins that are concentrated in chromatin subfractions enriched in DNA . These receptors appear to be DNA-binding proteins . In the present study, we utilized a DNA-cellulose binding assay to further examine the interactions of solubilized receptors with DNA . {125I}Triiodothyronine associates with receptors bound to DNA-cellulose, whereas free {I}triiodothyronine and {125I}triiodothyronine associated with other proteins does not . The DNA-receptor interactions appear to be strong enough to exist at physiological ionic strength since binding is 50% maximal ag 0.175 M NaCl and is only partly inhibited by Ca2+ and Mg2+ in the 1 to 5 mM range . Most, if not all, of the receptors are capable of DNA binding, and there are at least 80,000 receptor binding sites/diploid DNA (assuming one triiodothyronine binding site/receptor) . Binding of the receptor-{125I}triiodothyronine complexes to other DNAs and analogs was examined using a competition assay . There is similar binding by native and denatured DNA, gy eukaryotic DNA from different species and by prokaryotic DNA (Bacillus subtilis) . Binding by natural DNAs is more avid than by cytoplasmic RNA, nuclear RNA, poly(dA-dT)-poly(dA-dT), or poly(dG-dC)-poly(dG-dC) . Under these conditions, binding by tRNA and poly(dA) is insignificant, and the nucleotide monomers ATP and GTP have no detectable binding . These studies support the idea that the thyroid hormone receptor is a DNA-binding protein and that the interaction is a major determinant for receptor localization in chromatin . The competition studies suggest that the polynucleotide composition and/or conformation can have marked influences on the binding, and that multiple orders of binding affinity can exist . The presence of specific sequences cannot be excluded . However, the finding that receptors bind extensively and tightly to DNA suggests that receptors in chromatin may randomly bind to any available DNA, resulting in some of the receptors being at physiologically unimportant sites . If so, the several thousand hormone receptors present in each target cell may be required to enhance the possibility that some of the receptors are present at the actual sites of action.

Biochemistry, 1976 Nov 16, 15(23), 4962 - 6
Guanosine monophosphate reductase from Artemia salina: Inhibition by xanthosine monophosphate and activation by diguanosine tetraphosphate; Renart MF et al.; In the course of studies on the metabolic role of diguanosine tetraphosphate during development of Artemia salina, a guanosine monophosphate (GMP) reductase has been found in partially purified from the 150 000g Artemia cysts supernatant . From Lineweaver-Burk plots, two apparent Km values of 5 and 50 muM were obtained for GMP . Xanthosine monophosphate (XMP) is a very strong inhibitor of the reaction . In the presence of 1.5 muM XMP hyperbolic kinetics are found . Diguanosine tetraphosphate counteracts very effectively the inhibition of the activity by XMP, concomitantly changing to hyperbolic the kinetics of the enzyme, with a unique Km value of about 5 muM . The complex kinetic and the existence of allosteric e-fectors at physiological concentrations, together with our lack of success in resolving two isoenzymes, makes it very likely that GMP reductase presents negative cooperativity towards its substrate . The effect of diguanosine tetraphosphate on the enzyme is very specific; other structural analogues, diadenosine tetraphosphate and diguanosine triphosphate, tested a micromolar concentrations had no detectable effect on the enzyme . Guanosine triphosphate (GTP) (mM) was also able to counteract the inhibition of guanosine monophosphate (GMP) reductase by XMP . The properties of the Artemia GMP reductase are here compared with those of the similar enzyme from calf thymus and Escherchia coli . As a consequence, the regulation of eukaryotic GMP reductase is resulting to be quite different from that of the reductase from prokaryotes.

Experientia, 1976 Nov 15, 32(11), 1399 - 400
Macronuclear response of Paramaecium multimicronucleatum to L-lysine; Mallik U; A strain of Paramaecium multimicronucleatum was exposed to a medium containing L-lysine; the concentrations of the amino acid were 0.1%, 0.5% and 1.0% for different sets of experiments . In these two latter concentrations, the macronucleus of the ciliate broke down into innumerable small fragments, the microspheres . The micro-nuclei remained inert . The microspheres left the body of paramaecium as cell-free, self-duplicating entities constituted of DNA and RNA and enveloped by a protein coat . They had no nuclear membrane and they resembled the prokaryotes . Grown in culture medium with 0.1% horse serum, the microspheres transformed into small amoebae having typical eukaryotic features . These amoebae maintained a typical cyst-trophic cycle during the successive sub-cultures; they had no similarity with the paramaecia.

Lipids, 1976 Nov, 11(11), 808 - 13
Retarding effects of DNA on the autoxidation of liposomal suspensions; Pietronigro DD et al.; Deoxyribonucleic acid (DNA) is associated with the cell membrane of prokaryotes and the inner nuclear membrane of eukaryotes . The unsaturated fatty acids of phospholipids, which constitute the bilaminar structure of membranes, undergo autoxidation in the presence of O2 . Calf thymus DNA was incuabted with methyl archidonate-enriched phosphatidyl choline liposomes in order to study the effect of DNA upon the oxidation of phospholipids while present in their natural in vivo bilayer configuration . DNA retarded the rate of lipid oxidation as monitored by both diene conjugation and the TBA test, but it did not alter the induction period . These results suggest that DNA is scavenging free radicals produced within the phospholipid bilayer.

Eur J Toxicol Environ Hyg, 1976 Nov-Dec, 9(6), 323 - 33
Isolation and biochemical properties of toxic tryptic peptides of ricinotoxin from Ricinus communis seeds; Lugnier AA et al.; Tryptic hydrolysis conditions of ricinotoxin were studied in order to produce not only digestion of this glycoprotein but also still toxic tryptic peptides . No hydrolysis was obtained without prior denaturation . The best conditions of denaturation were obtained with 0.2 M guanidine hydrochloride and, to a lower extent, by heat treatment at 90 degrees C during 6 minutes . The hydrolysates were fractionated on Sephadex G100 column . In each case highly toxic peptide fractions were obtained which showed, like native ricinotoxin, a strong inhibitory action on the in vitro protein synthesis ina cell-free eukaryotic system but were without any action on a prokaryotic cell-free system.

Eur J Biochem, 1976 Nov 1, 70(1), 1 - 6
Interaction of rat-liver glucocorticoid receptor with DNA; Milgrom E et al.; The complex of {3H}dexamethasone and rat liver receptor binds to rat liver DNA . This interaction takes place only in the presence of hormone and is enhanced by 'activation' . No evidence of saturatability can be obtained with concentrations of steroid-receptor complexes corresponding to those observed physiologically in the intact liver cell . The binding is inhibited by high ionic strength and by millimolar concentrations of divalent cations . No species specificity has been observed: the complex binds equally well to prokaryotic and eukaryotic DNA'S . There was no difference between binding to native and denatured DNA . In comparable conditions twice as much {3H}dexamethasone-receptor complexes were bound by DNA than by rat liver nuclei . Thus, the interaction of steroid-receptor complexes with DNA probably does not correspond to the recognition of a few very specific sequences . It is however possible that this interaction is actually operating in vivo in the intact cell.

CRC Crit Rev Biochem, 1976 Nov, 4(2), 175 - 202
Prokaryotic DNA in nucleoid structure; Pettijohn DE; Recent studies of the structure of the bacterial nucleoid are reviewed . In the past 4 to 5 years results of electron microscopic and physical-chemical investigations of the isolated bacterial nucleoids have greatly advanced our understanding of this comparatively simple chromosome . Evidence for both long-range and short-range conformational organization of the packaged DNA has emerged, and preliminary characterization of the molecular interactions organizing this structure has been accomplished.

Biokhimiia, 1976 Nov, 41(11), 1915 - 27
{Chloroplast ribosomes}; Odintsova MS et al.; A brief review of modern concepts on the structure and properties of chloroplast ribosomes is given . An attention is paid to the similarity of 70S chloroplast ribosomes, 80S cytoplasmic ribosomes and ribosomes of prokaryotic type which is interesting from the viewpoint of the origin and evolution of plastids . Problems of rRNA and ribosomal proteins biosynthesis, of biogenesis and functions of chloroplast ribosomes are also considered.

Proc Natl Acad Sci U S A, 1976 Nov, 73(11), 3838 - 42
Biochemical construction of specific chimeric plasmids from ColE1 DNA and unfractionated Escherichia coli DNA; Collins CJ et al.; A series of chimeric plasmids was constructed using colicinigenic factor E1 (ColE1) DNA as the replicon and DNA fragments carrying the galactose or tryptophan operons from E . coli . Restriction endonuclease EcoRI digests of ColE1 DNA and various DNAs containing the trp or gal operons were joined by T4 polynucleotide ligase {polynucleotide synthetase (ATP), poly(deoxyribonucleotide):poly(deoxyribonucleotide) ligase (AMP-forming), EC 6.5.1.1} . Chimeric plasmids carrying the desired genes were selected after transformation of Trp- or Gal- cells with ligated DNA . By using this method, we constructed ColE1-gal and ColE1-trp chimeric plasmids in which the source of the bacterial gal and trp operons was an unfractionated EcoRI digest of total E . coli DNA . The frequency of recovery of such chimeric plasmids is 10 to 20 colonies per mug of ligated DNA used in the transformation step . The method utilized in this report for constructing specific chimeric plasmids from total E . coli DNA is very simple . It requires only endonuclease R-EcoRI and T4 polynucleotide ligase, both of which are commercially available . The yield of transformants suggests that this method will be useful for cloning and amplifying a wide variety of functionally defined genes from E . coli and other prokaryotic organisms.

Ann Immunol (Paris), 1976 Sep-Oct, 127(5), 607 - 31
The complete sequence of the murine monoclonal immunoglobulin MOPC 173 (IgG2a): genetic implications; Fougereau M et al.; The complete amino acid sequence of the murine monoclonal immunoglobulin MOPC 173 (IgG2a, kappa) is reported . The heavy chain contains 447 amino-acid residues, and one carbohydrate prosthetic group attached to the ASX residue 299 . The kappa light chain is composed of 214 residues . The H chains are covalently linked by 3 interchain disulfide bridges . The H-L bond-forming cysteine of the H chain is between the VH and the CH1 domain . Intrachain bridges are disposed linearly, according to the classical model . There is no simple relationship between the primary structure and any given function of a particular domain . This is presumably due to the fact that the selection pressure exerts itself on the three-dimensional structure which may retain a conserved general organization as a result of balanced multiple mutations . Selection seems to act in two ways: --horizontally, in a multigene system such as the immunoglobulin classes (C domains of the heavy chains), leading to interclass homologies which are particularly marked for all the COOH-terminal domains of H and L chains which have, in addition a fair degree of homology with human beta2 microglobulin (about 30% identities); --vertically, in which case strictly homologous domains appear extremely conserved between distinct animal species . Conservation of the VH domains seems just as high as conservation of the CH domains . The VH region contains 3 types of positions: invariant and subgroup characteristic ("framework") which may be accounted for by a rather small number of germ-line genes, and hypervariable for which the origin of diversity, somatic or germinal, cannot be decided from sequence data alone . Murine VK domains, although basically built according to the same pattern, show a much more marked polymorphism of the framework, which might necessitate a higher number of basic germ-line genes . Finally, a hypothetical model of the switch mechanism is proposed . Rotational symmetry regions can be deduced at the DNA level from the known amino acid sequences of the switch peptides for the three translocational systems: H, kappa and lambda . These would provide recognition signals for restriction-like enzymes such as those which operate in prokaryotes . An implication of this model is the definition of an exact limit between the V and the C regions of all immunoglobulin chains.

Cancer Res, 1976 Sep, 36(9 PT 2), 3394 - 8
Selective control of DNA helix openings during gene regulation; Frenster JH; DNA helices must undergo openings in the form of localized strand separations in order to permit the onset of RNA synthesis or DNA synthesis . The selective control of such DNA helix openings at particular gene loci is the critical feature of gene regulation in prokaryotes and eukaryotes.

Cancer Res, 1976 Sep, 36(9 pt.1), 3025 - 33
Increased attachment of nucleic acids to eukaryotic and prokaryotic cells induced by chemical and physical carcinogens and mutagens; Kubinski H et al.; Significantly enhanced attachment to Ehrlich ascites and Escherichia coli cells was observed for radioactive DNA and RNA in the presence of chemical mutagens and ultimate carcinogens . In some instances, formation of nucleic acid-protein adducts by these compounds further (or similarly) enhanced the binding . DNA irradiated with ultraviolet light in the presence of a protein bound more efficiently than either an unirradiated mixture of these two macromolecules or DNA irradiated alone . The spectrum of compounds tested and found active in this system includes alkylating agents, aromatic amines, and carcinogenic metals . Precarcinogens and nonultimate carcinogenic chemicals, as well as tumor-promoting agents, did not increase the binding . However, addition of extracts from mouse or rat livers activated precarcinogenic and proximate carcinogenic chemicals and resulted in enhanced cellular attachment of indicator nucleic acids in their presence . Possible usefulness of this test system for fast and efficient screening for environmental carcinogens and mutagens, as well as possible relevance of the observed phenomena to in vivo effects of chemical and physical carcinogens, is considered.

Eur J Biochem, 1976 Sep, 68(1), 245 - 54
Molecular organization in bacterial cell membranes . Sulfhydryl groups and disulfide bridges in Streptomyces albus and Escherichia coli K 12 cytoplasmic membranes; Azocar O et al.; Plasma membranes from Streptomyces albus had 5.2 mol of sulfhydryl groups and 6 mol of disulfide bridges/50 kg proteins whereas Escherichia coli membranes had 3.4 mol sulfhydryl groups and 4 mol disulfide bridges/50 kg protein . About 66% of the sulfhydryl groups of S . albus membranes and 22% of those of E . coli membranes were readily accessible to titration with 5,5'-dithiobis(2-dinitrobenzoic acid) . o-{3 Hydroxymercuri-2-methoxypropyl)-carbamyl}-phenoxyacetic acid (mersalyc acid) and p-chloromercuribenzoate were effective in solubilizing membrane proteins from the two bacteria . Other sulfhydryl group reagents, such as N-ethylmaleimide, iodoacetamide and iodoacetic acid, were less effective . Dithiothreitol affected the dodecylsulphate gel electrophoresis patterns of S . albus membranes and soluble fractions . This effect resulted from the reduction of pre-existing disulfide intramolecular bridges and some interchain disulfide formed during solubilization and/or storage . Dithiothreitol also affected the dodecylsulphate gel electrophoresis patterns of E . coli membranes and their soluble fractions . These results suggest that sulfhydryl groups and disulfide bridges play a role in the structural organization of these prokaryotic membranes.

Eur J Biochem, 1976 Sep, 68(1), 1 - 3
Indolmycin inhibits prokaryotic tryptophanyl-tRNA ligase; Werner RG et al.; Indolmycin specifically prevents the formation of tryptophanyl-tRNA in a prokaryotic system in vitro using Escherichia coli enzymes . However, the drug has little effect in an eukaryotic system in vitro (rat liver enzymes) . Analysis of the type of inhibition revealed that indolmycin competes with tryptophan as a pure competitive inhibitor of prokaryotic tryptophanyl-tRNA ligase.

Proc Natl Acad Sci U S A, 1976 Aug, 73(8), 2752 - 6
Bacteriophage T3 and T7 early RNAs are translated by eukaryotic 80S ribosomes: active phage T3 coded S-adenosylmethionine cleaving enzyme is synthesized; Anderson CW et al.; RNA transcribed in vitro from the early region of bacteriophage T3 or T7 was translated by cytoplasmic ribosomes which synthesized protein in cell-free systems prepared from mammalian cells and wheat germ . The proteins synthesized in vitro and their counterparts prepared from infected Escherichia coli comigrate by polyacrylamide gel electrophoresis with sodium dodecyl sulfate and are similarly affected by deletion or amber bacteriophage mutations . Bacteriophage T3 codes for an enzyme that cleaves S-adenosylmethionine and this activity was detected among the products of the mammalian cell-free system . Bacteriophage T3 or T7 RNA, after endoribonuclease III (EC 3.1.4.24) cleavage, gave higher levels of incorporation into phage T3 or T7 polypeptides than when an equivalent amount of the uncleaved RNA was added to the eukaryotic cell-free systems . Methylation of phage T3 or T7 RNAs is apparently not required for translation in either the wheat germ or mammalian cell-free system . The ability of T3 and T7 RNA to be translated in the presence of saturating amounts of natural eukaryotic mRNAs suggests that many prokaryotic genes introduced into mammalian cells might be expressed if they were transcribed in an appropriate form.

Can J Biochem, 1976 Aug, 54(8), 736 - 45
Quantitative effects of unsaturated fatty acids in microbial mutants . VI . Selective growth responses of yeast and bacteria to cis-octadecenoate isomers; Ohlrogge JB et al.; The full series of positional isomers of cis-octadecenoate were tested for their suitability in meeting the nutritional requirement for unsaturated fatty acids by mutants of Escherichia coli and Saccharomyces cerevisiae that were unable to synthesize unsaturated fatty acids . Quantitative comparisons of the efficiencies of the various isomers showed a range from 0-48 cells per femtomole for the prokaryotic cells and 0-5 for eukaryotic cells . The delta 5 isomer was much more effective than the delta 6 isomer with the bacterial cells whereas the reverse was true with the yeast cells . In general, isomers containing a cis ethylenic bond between carbons 7 and 12 were able to support extensive growth of either type of mutant . Since all of the various isomers were incorporated into cellular lipids by both types of microorganism, the different efficiencies observed in supporting growth were not a simple reflection of the inability of an acid to be esterified . The differences may reflect the suitability of the resultant esterified product to function as a normal membrane lipid . The contents of various fatty acids in the cellular phospholipids when growth ceases may have a linearly cumulative relationship to the degree of expansion of the acyl chains.

Fed Proc, 1976 Aug, 35(10), 2132 - 8
The origin and evolution of protein superfamilies; Dayhoff MO; The organization of proteins into superfamilies based primarily on their sequences is introduced: examples are given of the methods used to cluster the related sequences and to elucidate the evolutionary history of the corresponding genes within each superfamily . Within the framework of this organization, the amount of sequence information currently and potentially available in all living forms can be discussed . The 116 superfamilies already sampled reflect possibly 10% of the total number . There are related proteins from many species in all of these superfamilies, suggesting that the origin of a new superfamily is rare indeed . The proteins so far sequenced are so rigorously conserved by the evolutionary process that we would expect to recognize as related descendants of any protein found in the ancestral vertebrate . The evolutionary history of the thyrotropin-gonadotropin beta chain superfamily is discussed in detail as an example . Some proteins are so constrained in structure that related forms can be recognized in prokaryotes and eukaryotes . Evolution in these superfamilies can be traced back close to the origin of life itself . From the evolutionary tree of the c-type cytochromes the identity of the prokaryote types involved in the symbiotic origin of mitochondria and chloroplasts begins to emerge.

Biochem J, 1976 Jul 1, 157(1), 275 - 7
Higher-plant mitochondrial ribosomes contain a 5S ribosomal ribonucleic acid component; Leaver CJ et al.; Ribosomes from higher-plant mitochondria contain 5S rRNA, in contrast with the mitochondrial ribosomes of animals and fungi, in which such a component has not been detected . In common with the ribosomes of prokaryotes and chloroplasts, higher-plant mitochondrial ribosomes do not appear to contain an RNA equivalent to the 5.8 S rRNA that is found in eukaryoytes hydrogen-bonded to the largest of the cytoplasmic rRNA species.

J Gen Microbiol, 1976 Jul, 95(1), 45 - 53
Ultrastructure of Rothia dentocariosa; Roth GD et al.; Rothia dentocariosa was seen as a typical prokaryotic cell, lacking nuclear envelope, mitochondria and a reticulum with ribosomes . The plasma membrane was located close to and parallel to the wall . The outer limits of the wall were associated with what may be capsular or slime material . Chain-like filaments of thick walled coccoid cells underwent septation both transverse and parallel to the long axis of the chain . Side branching and terminal clavate forms were also present . These clavate forms may represent specialized cells during the life-cycle . Fragmentation of the chain resulted when the outer wall ruptured to release the coccoid bodies.

J Invest Dermatol, 1976 Jul, 67(1), 15 - 9
Regulation of cell cycles; Voorhees JJ et al.; Of the major achievements in cell biology during the last 25 years, none is more important than the understanding of regulation of cell cycles . In 1953 two fundamental observations concerning DNA were made . Watson and Crick suggested that the three-dimensional structure of DNA exists as a double helix with specific base pairings, and Howard and Pelc observed that DNA is replicated during a specific phase in the mitotic cycle . Thus developed the theory of cell cycles . Next, investigators explored which events occur during each phase of the cycle and what controls the readout of the genes of proliferation or differentiation . In 1961, Jacob and Monod proposed that for prokaryotic cells the operon is the mechanism which controls the readout of the genes; and by the end of the 1960s, several investigators had defined the role of cyclic AMP and its mechanism of action at the gene level . The control mechanisms of eukaryotic cells are less well defined . Basically there are two types of regulatory molecules: those that arrive at the cell surface and send messages inside the cell; and those that enter the cell, bind to receptors, and then enter the nucleus to interact with the genes . During the past five to ten years, the cell surface and its receptors have received considerable attention as the recognition and control areas for cell proliferation and differentiation, and currently the role of the cyclic nucleotides and prostaglandins is being investigated . Various model systems are now available for detailed studies of these control mechanisms.

Biochemistry, 1976 Jun 29, 15(13), 2817 - 23
A new mammalian DNA polymerase with 3' to 5' exonuclease activity: DNA polymerase delta; Byrnes JJ et al.; A new species of DNA polymerase has been purified more than 10 000-fold from the cytoplasm of erythroid hyperplastic bone marrow . This DNA polymerase, in contrast to previously described eukaryotic DNA polymerases, is associated with a very active 3' to 5' exonuclease activity . Similar to the 3' to 5' exonuclease activity associated with prokaryotic DNA polymerases, this enzyme catalyzes the removal of 3'-terminal nucleotides from DNA, as well as a template-dependent conversion of deoxyribonucleoside triphosphates to monophosphates . The exonuclease activity is not separable from the DNA polymerase activity by chromatography on DEAE-Sephadex or hydroxylapatite, and upon sucrose density gradient centrifugation the two activities cosediment at 7 S or at 11 S depending on the ionic strength . Both exonuclease and polymerase activities have identical rates of heat inactivation and both are equally sensitive to hemin and Rifamycin AF/013, inhibitors of DNA synthesis that act by binding to DNA polymerase and causing its dissociation from its template/primer . These results are consistent with the coexistence of two enzyme activities in a single protein.

Science, 1976 May 7, 192(4239), 524 - 9
Evolution of genome size by DNA doublings; Sparrow AH et al.; Logarithmic distributions of nucleic acid contents per genome of species within major phylogenetic groups of organisms tend to form several peaks . These peaks appear to represent intragroup doublings of DNA or RNA which, in the case of eukaryotes, are independent of polyploidy . This phenomenon has been termed cryptopolyploidy . There are numerical similarities in peak values for different taxonomic groups . A high degree of order is suggested when minimum values for the major phylogenetic groups are plotted against a series of theoretical doublings . These data demonstrate the apparent existence of an exponential periodicity over eight orders of magnitude, leading us to suggest an evolutionary continuity of doublings of a basic ancestral genome (of about 300 nucleotides), these doublings being independent of both chromosome number and ploidy level . This proposed continuity encompasses most major life forms and is generally concomitant with increasing evolutionary complexity, particularly in the prokaryotes and lower eukaryotes . Our interpretation of the data presented here must currently be viewed as speculative, and we do not propose that genome doubling is the only mechanism for genome evolution . However, we feel that the evidence is sufficient to warrant serious scrutiny of our proposals . We hope that this approach to a synthesis of available data will provoke discussion and will stimulate further work toward either supporting, modifying, or disproving our hypothesis.

Mol Gen Genet, 1976 May 7, 145(2), 119 - 23
Molecular evolution of 5S RNA; Hori H; Based on the comparative analyses of the primary structure of 5S RNAs from 19 organisms, a secondary structure model of 5S RNA is proposed . 5S RNA has essentially the same structure among all prokaryotic species . The same is true for eukaryotic 5S RNAs . Prokaryotic and eukaryotic 5S RNAs are also quite similar to each other, except for a difference in a specific region . By comparing the nucleotide alignment from the juxtaposed 5S RNA secondary structures, a phylogenic tree of nineteen organisms was constructed . The time of divergence between prokaryotes and eukaryotes was estimated to be 2.5 X 10(9) years ago (minimum estimate: 2.1 X 10(9).

Arch Microbiol, 1976 May 3, 108(1), 117 - 24
Growth and physiology of Candida utilis NCYC 321 in potassium-limited chemostat culture; Aiking H et al.; When grown in a defined simple salts medium, plus vitamins, Candida utilis displayed an absolute requirement for potassium . But the potassium content of this yeast was exceedingly variable and, with aerobic chemostat cultures (grown at a dilution rate of 0.1 h-1; 30 degrees C; pH 5.5), was low (less than 0.2%, w/w) when they were potassium-limited and high (greater than 2%, w/w) when glucose-limited . With potassium-limited cultures, the cell-bound potassium content also varied markedly with growth rate, though hardly at all with glucose-limited cultures; magnesium- and phosphate-limited cultures gave intermediate responses . Changes in cell-bound potassium content correlated only weakly with changes in the cellular contents of magnesium, phosphate and RNA, but strongly with changes in both the Yglucose and Y0 values, indicating an involvement of potassium in the generation of energy by oxidative phosphorylation reactions and/or the utilization of this energy for growth processes . Studies with isolated mitochondria revealed that potassium-limited organisms had a changed content of cytochrome b relative to cytochrome a, and lacked coupling at either site 2 or site 3 of the respiratory chain . These results are discussed in relation to the reported functions of potassium in the growth of micro-organisms, and the organizational differences between prokaryotic and eukaryotic cells.

J Biol Chem, 1976 Apr 10, 251(7), 2142 - 6
Single-stranded DNA structure and DNA polymerase activity in the presence of nucleic acid helix-unwinding proteins from calf thymus; Herrick G et al.; In the preceding articles we have described the isolation and some of the properties of two calf thymus proteins which bind selectively to single-stranded DNA and which appear analogous to previously isolated prokaryotic DNA-unwinding proteins . In the present work we demonstrate two further points of analogy . First, both the calf UP1 and the high salt eluting proteins form protein-rich complexes with single-stranded DNA, and hold this DNA in a rigid, extended conformation . Second, these proteins stimulate the calf thymus DNA polymerase-alpha; phage T4 gene 32-protein does not . The stimulation of a homologous DNA polymerase is characteristic of several prokaryotic DNA-unwinding proteins and is assumed to reflect their in vivo role in DNA synthesis.

J Biol Chem, 1976 Apr 10, 251(7), 2133 - 41
Nucleic acid helix-coil transitions mediated by helix-unwinding proteins from calf thymus; Herrick G et al.; We have studied nucleic acid double helix destabilization mediated by purified calf helix-unwinding proteins, measuring ultraviolet hyperchromicity to detect helix melting . Both calf unwinding protein 1 (UP1) and a high salt eluting protein fraction are found to depress strongly the helix melting temperature (Tm) of the synthetic alternating copolymers poly{d(AT)} and poly{r(AU)}, indicating that both DNA and RNA are recognized by these proteins . UP1 also destabilizes natural, GC-containing DNA helices, but to a smaller extent than observed with the above polymers . A simple model is presented to aid in the qualitative interpretation of the data, outlining the expected effect on the helix-coil transition of a protein ligand with differential affinity for the helix or coil form of nucleic acid . The observed helix-destabilizing effect of UP1 is dependent on the protein to nucleic acid ratio in an expected manner . Competition studies demonstrate a low, but appreciable affinity of UP1 for native DNA, opening the possibility that protein-mediated denaturation might be initiated by protein binding to the double helix . "Hairpin" helical regions of denatured DNA are strongly destabilized by UP1 . Despite the fact that removal of these hairpin helices might greatly facilitate DNA renaturation, we failed to observe renaturation from the UP1-DNA complex after a switch to helix-stabilizing conditions . Thus, UP1 shows an important difference from its presumed prokaryotic analogue, T4 gene 32-protein . Possible in vivo functions of the calf proteins are discussed in light of these observations.

J Biol Chem, 1976 Apr 10, 251(7), 2124 - 32
Purification and physical characterization of nucleic acid helix-unwinding proteins from calf thymus; Herrick G et al.; We have devised a general protein fractionation procedure which selects for eukaryotic DNA-binding proteins, some of which resemble DNA-unwinding proteins from prokaryotes . Proteins were selected which (a) pass through a native DNA-cellulose column, (b) bind to a denatured DNA-cellulose column, and (c) remain bound to the latter column during a rinse with a dilute solution of the sodium salt of the polyanion dextran sulfate . When this fractionation was applied to the soluble proteins fo calf thymus, three major protein species were recovered . The predominant one has an apparent molecular weight of about 24,000 in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, is isoelectric near neutrality, and elutes as a monomer from denatured DNA-cellulose at moderate NaCl concentrations . This protein, designated calf-unwinding protein 1 (UP1), has been purified to homogeneity . However, isoelectric focusing reveals four or five subspecies (apparently separated by single-charge differences) which differ appreciably in their affinities for DNA . Two other major proteins are obtained which have apparent molecular weights in sodium dodecyl sulfate of 33,000: the first, which elutes with low salt from DNA-cellulose as a homogeneous preparation, appears to be a basic protein (although it is clearly not a histone); the other, which elutes from DNA-cellulose as the major component of a "high salt eluting fraction," is an acidic protein which co-purifies with less prominent species of higher molecular weights . Proteins similar to each of these three major calf thymus proteins have been observed by us and others in tissue culture cells of mouse, hamster, monkey, and humans, suggesting their wide occurrence among eukaryotes.

J Biol Chem, 1976 Apr 10, 251(7), 2005 - 14
Purification and characterization of a prokaryotic glucoprotein from the cell envelope of Halobacterium salinarium; Mescher MF et al.; The glycoprotein which accounts for approximately 50% of the protein and all of the nonlipid carbohydrate of the cell envelope of Halobacterium salinarium (Mescher, M . F., Strominger, J . L., and Watson S . W . (1974) J . Bacteriol . 120, 945-954) has been purified and partially characterized . The glycoprotein has an apparent molecular weight of 200,000, is extremely acidic, and has a carbohydrate content of approximately 10 to 12% . The carbohydrate included neutral hexoses, amino sugar, and uronic acid . Information regarding the number, composition, and mode of attachment of the carbohydrate chains was obtained by isolation and examination of the glycopeptides derived from degradation of cell envelope protein with trypsin and pronase . Trypsin digestion resulted in two glycopeptides . One of these was large (approximately 55,000 daltons) and had most of the neutral hexose linked to it . The carbohydrate moieties consisted of di- and trisaccharides of glucosylgalactose and (uronic acid, glucose)-galactose attached via O-glycosidic linkages between galactose and threonine . The other tryptic glycopeptide had a relatively large heterosaccharide attached to it via an alkaline-stable linkage . The heterosaccharide contained 1 glucose, 8 to 9 galactose, 1 mannose, and 10 to 11 glucosamine residues, and approximately 6 residues of an unidentified amino augar . The alkaline stability of the linkage and the amino acid composition of glycopeptides resulting from Pronase digestion of the tryptic glycopeptide showed that the heterosaccharide was attached to an asparagine residue, presumably via an N-glycosylamine bond to the amide group . The intact glycoprotein has a single N-linked heterosaccharide, 22 to 24 O-linked disaccharides, and 12 to 14 O-linked trisaccharides per molecule . N- and O-glycosidic linkages are the most common carbohydrate-protein linkages in mammalian glycoproteins but, to our knowledge, this is the first report of either type of linkage in a prokaryotic cell envelope protein.

Biochemistry, 1976 Apr 6, 15(7), 1362 - 9
Toward an understanding of the formylation of initiator tRNA methionine in prokaryotic protein synthesis . II . A two-state model for the 70S ribosome; Petersen HU et al.; The 70S ribosomes can select the proper initiator tRNA between Met-tRNAfMet and fMet-tRNAfMet . Experiments on binding and on formation of aminoacylpuromycin, as a function of magnesium, potassium, or initiation factors, suggest a two-state equilibrium for 70S particles, involving a minor, active conformation and a major one which is not readily active . The formyl group would act as a specific trigger to select the active conformation . Experimental results are interpreted following this simple model and equilibrium parameters, together with kinetic constants of the peptidyltransferase activity, are presented.

Biochemistry, 1976 Apr 6, 15(7), 1357 - 62
Toward an understanding of the formylation of initiator tRNA methionine in prokaryotic protein synthesis . I . In vitro studies of the 30S and 70S ribosomal-tRNA complex; Petersen HU et al.; Formation of the 30S-tRNA initiation complex of Escherichia coli with nonformylated initiator tRNA is stimulated by all three initiation factors and is messenger dependent, whereas the complex formation involving the 70S ribosomes is strongly inhibited by initiation factors when the nonformylated species is used . When the 30S-Met-tRNAfMet complex is first formed and the 50S ribosomal subunit added subsequently, there is no significant inhibition by initiation factors and the nonformylated initiator tRNA is puromycin reactive . This leads to the conclusion that the formylation of the methionyl initator tRNA is only obligatory when polypeptide synthesis is initiated by nondissociated 70S ribosomes.

Biochemistry, 1976 Mar 9, 15(5), 974 - 9
Phosphatidylglycerol biosynthesis in Bacillus licheniformis Resolution of membrane-bound enzymes by affinity chromatography on cytidinediphospho-sn-1,2-diacylglycerol Sepharose; Larson TJ et al.; Cytidinediphospho-sn-1,2-diaclglycerol (CDP-diglyceride) has been covalently linked to Sephrose 4B via adipic acid dihydrazide spacer arm forming an effective affinity chromatography column . This liponucleo-tide ligand and sn-glycero-3-phosphate are subtracts for the formation of 3-sn-phoshatidyl-1'-sn-glycero-3'-phosphate (PGP) catalyzed in both eukaryotic and prokaryotic organisms by sn-glycero-3-phosphate: CMP phosphatidlytranferase (PGP synthetase) . Using this CDP-diglyceride Sephrose affinity column we were able to resolve the membrane associated 3-sn-phosphatidyl'1-sn-glycerol (PG) synthesizing system present in Bacillus licheniformis into two activities . A PGP synthetase activity was adsorbed to the affinity column and was eluted using buffer containg CDP-diglyceride; a PGP phosphatease acactivity had no affinity for the column . Both PGP synthase and PGP phosphatase of B . licheniformis were associated with a membrane component of the cell as evidenced by sucrose gradient centrifugation, differential centrifugation, and solubilization by buffers containing detergent...

J Bacteriol, 1976 Mar, 125(3), 1156 - 62
Ultrastructure of rigid and lignified forage tissue degradation by a filamentous rumen microorganism; Akin DE; A small (less than 1 mum)-filamentous, branching microorganism was observed in Gram-stained smears of the rumen microflora and was found to degrade tissues in forage samples incubated in vitro and in vivo with rumen fluid and observed by scanning and transmission electron microscopy . The microbe had prokaryotic cytoplasmic features and a gram-positive type of cell wall structure . Round to oval bodies apparently attached to hyphae resembled the sporulation pattern reported for Micromonospora . Filaments and rod and coccal forms of the microbe degraded rigid forage cell walls and lignified, thick-walled sclerenchymal cells . Location of the microbe at a slight distance from the degraded zones suggested the action of extracellular enzymes . The presence of a microbe with the capability of degrading lignified tissue represents an important and unique function in the rumen ecosystem.

Proc Natl Acad Sci U S A, 1976 Mar, 73(3), 852 - 6
Surface membrane carbohydrate alterations of a flagellated protozoan mediated by bacterial endosymbiotes; Dwyer DM et al.; Crithidia oncopelti, a parasitic trypanosomatid protozoan of insects, normally contains intracellular symbiotic bacteria . As shown earlier, the protozoa can be rid of their endosymbiotes by chloramphenicol, producing a symbiote-free cell line . Here surface-membrane carbohydrate ligands of the symbiote-containing and symbiote-free strains were compared by lectin-mediated agglutination, lectin-ultrastructure localization . {3H} lectin-binding, and fluorescent lectin staining . Symbiote-free organisms consistently had 3-fold higher agglutination titers than symbiote-containing cells with concanavalin A . Conversely, symbiote-containing flagellates had 2- to 3-fold greater agglutination titers with a fucose-binding lectin than symbiote-free organisms . Ultrastructure results showed that more of concanavalin A-horseradish peroxidase-diaminobenzidine reaction product was present at the surface of symbiote-free than on symbiote-containing cells . Treatment with {3H}concanavalin A revealed that surface membrane sites available per cell for {3H}lectin-binding ranged from 6.2 to 7.4 x 10(4) and from 24 to 27 x 10(4) for symbiote-containing and symbiote-free organisms, respectively, i.e., the mean binding level of the latter for the lectin was 3.5 times greater than that of the former . Moreover, symbiote-free cells fluoresced more than symbiote-containing organisms after staining with fluorescein-labeled concanavalin A . Apparently, the prokaryotic endosymbiotes somehow alter the quantity of saccharide ligands in the C . oncopelti surface membrane.

J Mechanochem Cell Motil, 1976 Mar, 3(3), 207 - 17
Locomotion of flagellates with mastigonemes; Brennen C; Theoretical hydrodynamic analyses of the locomotion of flagellates with mastigonemes are presented and particular comparison is made within experimental data on Ochromonas malhamensis . The first part of the paper analyses locomotion assuming the mastigonemes are rigid and maintain a fixed and normal position relative to the flagellum . The predicted propulsive velocity of 60 mum/sec for Ochromonas agrees well with the observed values of 55-60 mum/sec . It is shown that the propulsive system of Ochromonas represents a compromise between the need for efficient rectilinear propulsion and the need to manoeuvre and accelerate . The effect of rigid mastigonemes which are maintained at non-zero angles to the flagellar normal is also calculated and demonstrates a significant degradation of performance when this angle is greater than about 10 degrees . The latter part of the paper investigates the more complex but more realistic situation in which the mastigonemes flex during the motion according to the instantaneous hydrodynamic forces imposed upon them . The cyclical flexing history of a mastigoneme with passage of a flagellar wave and the consequent velocity of propulsion are obtained for a variety of geometric configurations and structural mastigoneme stiffnesses . It is demonstrated that there exists a relatively small transition range in the values of mastigoneme flexibility below which the mastigonemes are essentially rigid and above which they become totally ineffective hydrodynamically so that the flagellum can be regarded as essentially smooth . Since the transition value of the modulus of elasticity is about 5 dynes/mum2 (or stiffness of 3.5 X 10(-16) dyne cm2) for the mastigonemes of Ochromonas it would appear that the actual value must be in excess of this . Comparison is made with the structural properties of the micro-tubules in eukaryote cilia and flagella and with prokaryote flagella . The latter comparison suggests that the mastigonemes of Ochromonas are just rigid enough to produce the observed propulsive effect.

Proc Natl Acad Sci U S A, 1976 Feb, 73(2), 563 - 7
Visualization of prokaryotic DNA in a regularly condensed chromatin-like fiber; Griffith JD; Electron microscopy of disrupted Escherichia coli cells under certain conditions revealed loops of a fiber 120 A in diameter which were attached to the cell envelope and showed a 130 A repeating beaded substructure . These fibers were detected only when the cells were lysed in 0.15 M NaCl solutions directly on the electron microscope supporting films and if the dehydration steps began within 2 min of lysis . Under these conditions examination of cells lysogenic for phage lambda after superinfection with lambda wild type or deletion mutants disclosed short loops of a 120 A diameter fiber free of the cell envelope . Because the contour length of these loops was proportionate to the DNA content of the superinfecting lambda phage, it was concluded that the fibers contained DNA condensed 6.5-fold in blocks of about 250 base pairs.

Proc Natl Acad Sci U S A, 1976 Feb, 73(2), 405 - 9
Position of aminoacylation of individual Escherichia coli and yeast tRNAs; Hecht SM et al.; Transfer RNAs terminating 2'-or 3'-deoxyadenosine were prepared from unfractionated E . coli and yeast (Saccharomyces cerevisiae) tRNAs and purified to remove unmodified tRNAs . The modified tRNA species were assayed for aminoacylation with each of the 20 amino acids to determine the initial position of tRNA aminoacylation . The E . coli and yeast aminoacyl-tRNA synthetases specific for arginine, isoleucine, leucine, methionine, phenylalanine, and valine, as well as the E . coli glutamyl-tRNA synthetase, aminoacylated only those cognate tRNAs terminating in 3'-deoxyadenosine (i.e., those having a 2'-OH group) . On the other hand, those E . coli and yeast synthetases specific for alanine, glycine, histidine, lysine, proline, serine, and threonine, as well as the yeast synthetase specific for glutamine, utilized exclusively those tRNAs having an available 3'-OH group on the 3'-terminal nucleoside, while the E . coli and yeast synthetases specific for asparagine, cysteine, and tyrosine, and the yeast aspartyl-tRNA synthetase, utilized both of the modified cognate tRNAs . The only observed difference in specificity between the E . coli and yeast systems was for tRNATrp, which was aminoacylated on the 2'-position in E . coli and the 3'-position in yeast . The results indicate that the initial position of aminoacylation is not uniform for all tRNAs, although for individual tRNAs the specificity has been conserved during the evolution from a prokaryotic to eukaryotic organism.

J Protozool, 1976 Feb, 23(1), 13 - 28
Dinoflagellate evolution: speculation and evidence; Loeblich AR 3rd; Nuclear features of dinoflagellates that were used originally to support the Mesocaryota concept are reviewed . The fibrillar diameter of dinoflagellage chromatin, low level of chromosomal basic proteins, membrane attachment of chromosomes and swirl pattern observed in sectioned chromosomes are features that support a prokaryotic affinity . The presence of repeated and highly complex DNA, a S-phase of DNA synthesis in the cell cycle, presence of basic proteins, and the reinterpretation of extranuclear microtubules as a spindle support the contention that dinoflagellates are eukaryotes . This combination of prokaryotic and eukaryotic features suggests that dionflagellates are a geologically old group and that perhaps they diverged from the higher eukaryotic lineage before evolution of eukaryotic chromatin but after the evolution of repeated DNA . The 2 patterns of carotenoid composition exemplified by the presence of peridinin or fucoxanthin suggest separate origins of dinoflagellate plastids, perhaps by prokaryotic and eukaryotic capture . It is suggested that the species possessing fucoxanthin obtained their plastids by capture of photosynthetic eukaryotes.

J Protozool, 1976 Feb, 23(1), 48 - 56
Search for clues to the evolutionary meaning of ciliate phylogeny; Hutner SH et al.; Progress in ciliatology and in allied fields may demystify ciliate phylogenetics . Concentration on hymenostomes (mainly Tetrahymena and Paramecium) may have obscured directional features of ciliate physiology in phylogenetic problems . Therefore, means are suggested for "domesticating" the presumptively primitive, predominantly marine, sand-dwelling gymnostomes having nondividing macronuclei . The prize quarry is the marine psammophile Stephanopogon whose homokaryotic condition may mark it as a living fossil . Eventual axenic cultivation of these "primitive" ciliates may be aided by use as food of easily grown photosynthetic prokaryotes, some isolated from the marine sulfuretum or adjacent aerobic muds and sands where "karyorelictid" ciliates flourish.

J Protozool, 1976 Feb, 23(1), 41 - 7
Phylogenetic origin of the chloroplast; Buetow DE; The 16S ribosomal RNA of the chloroplast of Euglena gracilis strain Z has been characterized in terms of its 2-dimensional electrophoretic "fingerprint" (T1 ribonuclease) . Over 100 spots were resolved on the "fingerprint" and each spot was characterized as to which RNA oligonucleotide fragment(s) is contained . When compared to similar analyses of prokaryotic 16S rRNAs and eukaryotic cytoplasmic 18S rRNAs, the chloroplast 16S rRNA was a typically prokaryotic RNA, but bore little if any relationship to eukaryotic 18S rRNAs . Therefore, the cistrons for chloroplast 16S rRNA are related to the equivalent prokaryotic cistrons, but, apparently, are not related to the equivalent eukaryotic cistrons . Among the organisms available for comparison, the Euglena chloroplast 16S rRNA appears most closely related to the 16S rRNA of the eukaryote, Porphyridium cruentum (a red alga), and at least distantly related to the 16S rRNAs of the blue-green algae and perhaps also to the bacilli.

Proc Natl Acad Sci U S A, 1976 Feb, 73(2), 472 - 5
Primary structure determination of two cytochromes c2: close similarity to functionally unrelated mitochondrial cytochrome C; Ambler RP et al.; The amino-acid sequences of the cytochromes c2 from the photosynthetic non-sulfur purple bacteria Rhodomicrobium vannielii and Rhodopseudomonas viridis have been determined . Only a single residue deletion (at position 11 in horse cytochrome c) is necessary to align the sequences with those of mitochondrial cytochromes c . The overall sequence similarity between these cytochromes c2 and mitochondrial cytochromes c is closer than that between mitochondrial cytochromes c and the other cytochromes c2 of known sequence, and in the latter multiple insertions and deletions must be postulated before a match can be obtained . Nevertheless, these two cytochromes c2 show no better reactivity with the mitochondrial cytochrome c oxidase than do the less well-matched cytochromes c2 . The bearing of these findings on possible evolutionary relationship between mitochondria and prokaryotes is discussed.

J Biol Chem, 1976 Jan 10, 251(1), 137 - 40
Specific binding of Excherichia coli chain Initiation factor 2 to fMet-tRnafMet; Majumdar A et al.; A stable Escherichia coli IF-2-fMet-tRNAfMet complex is formed upon incubation of IF-2 (prokaryotic initiation factor) with fMet-tRNAfMet is the presence of 50 mM Tris-HCl, pH 7.0, 100 mM NH4Cl, and 7 mM 2-mercaptoethanol . The complex thus formed is retained on a Millipore filter and is assayed accordingly . Complex formation does dot require GTP, is unstable in the presence of 5 mM Mg2+, and is specific for fMet-tRNAfMet . Other amino acyl-tRNAs or deacylated tRNAs do not form such a complex with IF-2 . A crude ribosomal high salt wash preparation contains other protein factors which bind unspecifically to RNAs under the above binding conditions . One of these factors elute similarly to IF-1 on DEAE-cellulose chromatography . Extensively purified IF-1 and IF-3 show weak and unspecific RNA-binding activities . The RNA-protein complex formed in each of the above cases, like the IF-2-fMet-tRNAfMet complex, is retained on Millipore filter and is sensitive to Mg2+.

Can J Biochem, 1976 Jan, 54(1), 32 - 41
Enzymes of the orotate biosynthetic pathway in Crithidia fasciculata; Kidder GW et al.; A study of the enzymes of the orotate biosynthetic pathway in the kinetoplasid flagellate Crithidia fasciculata has revealed a number of differences between them and those of other organisms, either prokaryotic or eukaryotic . Carbamyl phosphate synthesis could not be demonstrated in cell-free extracts . However, the incorporation of both CO2 and the ureide carbon of citrulline into pyrimidines occurs in growing cells, the latter predominating over the former . The aspartate transcarbamylase of the flagellate has properties which are similar to those of this enzyme as it occurs in mammals rather than other microorganisms . Two enzymes, dihydroorotate synthetase and dihydroorotate hydrolase, are present, the former being responsible for the conversion of carbamylasparate to dihydroorotate . Dihydroorotate hydroxylase, a soluble enzyme requiring a reduced pteridine as a cofactor, converts dihydroorotate to orotate . The hydroxylase is inhibited by orotate, but not by pyrimidine or purine ribonucleotides . Thus orotate serves to control its own biosynthesis.

Arzneimittelforschung, 1976, 26(5), 765 - 9
New data on the mechanism and speed of action of nitroimidazoles on prokaryota and eukaryota with and without mitochondria; Carneri I et al.; The spectrum of action of nitroimidazoles ranges from anaerobic bacteria to aerobic bacteria which are also capable of growth, although sometimes with difficulty, in anaerobic atmosphere and to protozoa without and with mitochondria; in the latter case the anti-protozoal activity depends on the importance of the extramitochondrial enzymes which respond to nitroimidazoles . The more anaerobic the organisms, the greater their sensitivity . In the most sensitive protozoa, the trichomonads, most of the enzymatic reactions inhibited by these drugs take place in the hydrogenosomes; these are cytoplasmatic organelles surrounded by a membrane whose disintegration, in fact, is the first visible effect of the action of the nitroimidazoles . Various nitroimidazoles act with different speed on these and other protozoa, whose membranes can difinitely possess different degrees of permeability towards substances with different chemico-physical characteristics . In the treatment of trichomoniasis, the specific speed of action of a drug is perhaps as important as its half-life in man.

Z Allg Mikrobiol, 1976, 16(3), 201 - 5
{Microscopic studies of Streptomyces hygroscopicus growth kinetics}; Schuhmann E et al.; Growth kinetics, branch formation, and cytological properties of mycelial growth of Streptomyces hygroscopicus on solid media were investigated by phase-contrast microscopy using a microculture method . Measurements were made on taken photographs of the growing hyphae from the beginning of spore germination up to maximal 18 hours . The specific growth rate of the germ tube was much higher than the specific growth rate of the mycelium . The doubling time of the total length of the mycelial hyphae and the doubling time of branch formation was quite the same for the period investigated . After a short time of outgrowth each individual hypha grows at a constant rate, i.e . the length increases linearly, but the growth kinetics of the whole mycelium becomes exponentially by branching . It seems, that nucleoids only divide in that part of a hypha between the tip and the nearest branch . A cell unit (1.4-1.9 mum on different media) could be calculated by the length of a hypha and the number of nucleoids . A hypha is growing with the cell unit at the tip or with the polar cap only . No interkalary growth in length could be found . Branches were formed only up to about 100 mum from the tip on complex medium and up to about 50 mum from the tip on mineral salt medium . A simple method of mycelial growth has been developed . Some properties showing the connection between Streptomycetes and prokaryotic organisms on one hand and hyphal growing fungi on the other hand are discussed.

Folia Parasitol (Praha), 1976, 23(1), 33 - 7
Circular DNA and cardiolipin in hydrogenosomes, microbody-like organelles of trichomonads; Cerkasovova A et al.; Circular molecules of DNA approximately 3 mum in length were revealed by electron microscopy in deproteinized extracts prepared from purified hydrogenosomal fraction of a protozoan Tritrichomonae foetus . This fraction contained also cardiolipin amounting to approximately 14.4% of its total phospholipids, as detected by thin-layer chromatography and quantitative phosphorus measurement . These characteristics extend a number of biochemical properties of hydrogenosome shared also by mitochondria and by prokaryotic cells.

Acta Biochim Pol, 1976, 23(4), 341 - 52
Proteins of yeast ribosomal subunits: number and general properties; Grankowski N et al.; 1 . Saccharomyces cerevisiae at the early stationary phase of growth accumulate 80 S ribosomes, easily dissociating into subunits, which retain full activity in phenylalanine polymerization in vitro . A simplified and efficient technique for large-scale preparation of yeast ribosomal subunits is proposed . 2 . Presence of 34 proteins in 40 S subunit and 42 proteins in 60 S subunit was demonstrated by two-dimensional acrylamide-gel electrophoresis . Both ribosomal subunits contain acidic proteins: three in 60 S and six or seven in 40 S subunit . It seems that two of them correspond to prokaryotic proteins, L7 and L12 . The total number of yeast ribosomal proteins is similar to those obtained for other Eukaryota.

Med Pediatr Oncol, 1976, 2(3), 259 - 63
SV40 DNA sequences as an example of the structure of genes functioning in animal cell nuclei; Weissman SM et al.; Recent studies of the structure of messenger RNA have demonstrated the existence of untranslated sequences of the 3' and 5' end of the messages . In addition analysis of transcription in vitro has indicated that the nucleotide sequence U6 purine may be part of a transcription termination signal in prokaryotes . Recently it has been possible to determine the sequence of extensive portions of the DNA of SV40 virus . This article reviews the analogies between certain of these sequences and sequences available from prokaryotic messengers and DNAs . Unusual structures, including blocks of AT-rich and GC-rich segment sections and symmetric regions in the DNA near the origin of DNA replication, have been demonstrated and the distribution of stretches of 6 or more deoxyadenylic acids in the DNA of SV40 is consistent with some rho for these sequences in animal cells, either as terminators of transcription or as sites where degradation of transcripts is initiated or sites related to the selective rejection or degradation of transcipts.

J Mol Evol, 1975 Dec 31, 7(1), 75 - 86
Evolution of 5sRNA; Hori H; The evolution of 5sRNA of 17 organisms ranging from human to bacteria has been studied using a sequence homology analysis . The evolutionary rate of 5sRNA genes has been estimated to be 2.2x10(-10) replacement per one nucleotide site per year . This value is about the same as that of cytochrome C or tRNA's (congruent to 2x10(-10)) . A phylogenic tree of these organisms including both eukaryotes and prokaryotes has been constructed from the evolutionary distances (the rate of nucleotide substitution per site) data . The time of divergence of prokaryotes and eukaryotes was estimated to be greater than or congruent to 1.75x10(9) years ago and the branching order in eukaryotic kingdoms is consistent with the traditional order . Blue-green algae separated from the bacterial stem greater than or congruent to 1.3x10(9) years ago after eukaryotes had branched.

J Mol Evol, 1975 Dec 31, 7(1), 1 - 57
The appearance of new structures and functions in proteins during evolution; Zuckerkandl E; The likelihood of a de novo generation of classes of efficient proteins through neoformation of DNA, through modification of expressed DNA, and through modification of nonexpressed DNA is examined . So is the likelihood that newly formed inefficient enzymes be turned into efficient enzymes . The conclusions are that neither gene duplicates nor dormant genes represent promising materials for a de novo generation of protein classes, that (with exceptions) such generation is unlikely to have taken place in recent evolution, that new structural genes must nearly consistently derive from preexisting structural genes, and that new functions can be evolved only on the basis of old proteins . Conditions of protein evolution in prokaryotes suggest that the saltatory formation of protein classes is as unlikely in prokaryotes as in eukaryotes . Data on the history of a few protein classes are reviewed to illustrate the preceding inferences . The analysis leads to the hypothesis that most protein classes originated before the major elements of the translation apparatus of modern cells were fully evolved . If simple sequence DNA is turned into structural genes by evolution, this process (again with exceptions) is considered to have taken place only at that very remote period . A polyphyletic origin of proteins is thought to date back to the same era . It is proposed that the development of genic multiplicity and of marked structural and functional diversity of proteins may have come about in the earliest cells primarily through the independent generation of structurally different polymerases in different protocells, followed by cell conjugation and the subsequent use by enriched cells of supernumerary types of polymerase for evolving further functions . Functional growth, as it took place at early times, is briefly discussed as well as functional change . The foundations for new functional developments in old proteins are analyzed . In considering the evolutionary recovery of lost functions, aspects of cell differentiation and gene regulation are linked with the evolutionary picture . The distinction between eurygenic and stemogenic control of gene activity is used . Next to gene deletion, cell and tissue deletion is held to be an event of general evolutionary significance, through cell and tissue origination that presumably accompanies the restoration of a lost molecular function.

Mol Gen Genet, 1975 Dec 30, 142(3), 239 - 49
The generation of a ColE1-Apr cloning vehicle which allows detection of inserted DNA; So M et al.; A 3.2 Mdal sequence of DNA, TnA, which contains the ampicillin (Ap) resistance determinant has been translocated from an R plasmid to the plasmid ColE1 . A total of 12 isolates were studied . There are at least 8 sites in ColE1 at which TnA has inserted . Insertion at five of these has resulted in a Col-phenotype . One ColE1-Apr plasmid, RSF2124, was examined further and its replication properties are found to be similar to that of the parent plasmid . RSF2124 appears to be a useful plasmid vehicle for the molecular cloning of DNA from diverse prokaryotic sources: it codes for readily detectable Ap resistance and contains a single EcoRI site in a gene affecting colicin biosynthesis so that it is unable to produce colicin upon ligation to other DNA.

Proc Natl Acad Sci U S A, 1975 Dec, 72(12), 4830 - 4
Separation of lymphocyte chromatin into template-active fractions with specificity for eukaryotic RNA polymerase II or prokaryotic RNA polymerase; Magee BB et al.; When chromatin prepared from WI-L2 lymphocytes by low salt extraction and shearing is centrifuged on a glycerol gradient, one area of the gradient yields chromatin enriched in template activity for Escherichia coli DNA-dependent RNA polymerase (EC 2.7.7.6; nucleosidetriphosphate:RNA nucleotidyltransferase) as compared to Saccharomyces cerevisiae RNA polymerase II (or B) . Another area yields chromatin preferred by the eukaryotic enzyme . Kinetic studies indicate that the differences in activity cannot be explained by differences in affinity of the enzymes for the various templates . The DNA isolated from either fraction has a molecular weight of 8.5 X 106 . The "yeast active" fraction seems enriched in proteins . Mixing experiments indicate that the yeast enzyme does not alter the template in such a way as to improve it for the bacterial enzyme.

Can J Biochem, 1975 Dec, 53(12), 1288 - 300
A high molecular weight dihydro-orotate dehydrogenase of Neurospora crassa . Purification and properties of the enzyme; Miller RW; Some of the unusual molecular and catalytic properties of a high molecular weight dihydro-orotate dehydrogenase (DHOD) from Neurospora crassa have been determined . Comparison of the properties of this enzyme with the properties of the soluble biosynthetic enzyme of prokaryotes has revealed several important differences . The fungal enzyme is located in a mitochondrial membrane in a position consistent with linkage with the respiratory chain through ubiquinone (Miller, R . W.: Arch . Biochem, Biophys . 146, 256-270 (1971)) . Release of the enzyme from the membrane results in a solubilized protein complex containing bound lipids and inactive hydrophobic proteins . Non-specific protein aggregation is minimized during purification by Triton-X-100 and phospholipase treatments . The catalytically active enzyme has an apparent molecular weight of 210 000 . In contrast to soluble DHOD preparations the high molecular weight enzyme has no endogenous dihydro-orotate oxidase (EC 1.3.3.1) activity and is relatively insensitive to inactivation by sulfhydryl-reactive reagents in the presence of dihydro-orotate (DHO) . The enzyme activity is highly sensitive to conditions causing oxidation of flavin mononucleotide (FMN) . The activity cannot be restored by cysteine or other means . FMN is present in all purified preparations in a bound, non-fluorescent (reduced) form until dihydro-orotic acid is removed or oxidized . Catalytic efficiency of the purified enzyme was 12 000 mol DHO oxidized per minute per mole FMN . This high turnover rate is due in part to the small flavin content of the purified enzyme, equivalent to 1 mol FMN per 120 000 g of catalytically active protein . Iron was detected in the purified enzyme by atomic absorption spectroscopy but labile sulfide was absent . Thenoyltrifluoroacetone, an iron chelator, only partially inhibited DHO oxidation regardless of electron acceptor . Fatty acids interact with a hydrophobic site of the enzyme in non-competitive fashion but under certain conditions appear to significantly alter the Km for ubiquinone . Orotate, by comparison, is a purely competitive inhibitor . Both types of inhibitor may function to regulate the biosynthesis of orotate in vivo . Superoxide anion is not produced in significant quantities by the DHO-reduced enzyme unless both ubiquinone and a suitable single electron carrier such as phenazine methosulfate are present . DHOD has been proposed as a source of superoxide anion in mammalian mitochondria (Forman, H . J . & Kennedy, J . A.: J . Biol . Chem . 250, 4322-4326 (1975)).

Eur J Biochem, 1975 Nov 1, 59(1), 35 - 42
Nucleotide sequence of 5-S RNA from Bacillus licheniformis; Raue HA et al.; The complete nucleotide sequence of 5-S RNA from Bacillus licheniformis was determined by analysis of complete and partial digests obtained with either T1 or pancreatic ribonuclease . The molecule was found to have a length of 116 nucleotides and may possess a minor sequence heterogeneity . There is a large degree of homology between the sequence of B . licheniformis 5-S RNA and those published for 5-S RNA from B . megatherium and B . stearothermophilus . The difference between the three 5-S RNA species are limited mainly to the two terminal and one internal sequence . B . licheniformis 5-S RNA contains the sequence U95-G-A-G-A-G100, which in B . subtilis has been implicated in the processing of precursor 5-S RNA . Possible models for the secondary structure of prokaryotic 5-S RNA are discussed on the basis of the results of limited digestion of B . licheniformis 5-S RNA by ribonuclease T1.

Mikrobiologiia, 1975 Nov-Dec, 44(6), 1107 - 11
{Technics for isolation of ATP from microorganisms}; Aksenov SI et al.; A technique for isolation of ATP from microorganisms is suggested . The technique is based on increasing permeability of the cell membrane for substances of low molecular weight during dehydration . Treatment of the dry biomass with boiling water gives a higher yield of ATP from the cells of eukaryote and prokaryote microorganisms as compared with other techniques, and permits to register the amount of APT at the moment of experiment.

FEBS Lett, 1975 Oct 15, 58(1), 112 - 8
Stimulation by ATP of protein initiation in a prokaryotic organism, B . stearothermophilus; Kay AC et al.; In contrast to E . coli ribosomes, with B . stearothermophilus ribosomes initiation complex formation is stimulated by ATP as well as GTP, but maximum stimulation occurs when both the nucleotides are present; and their terminal phosphate must be hydrolysable . In the presence of ATP and GTP, B . stearothermophilus ribosomes synthesize a highly phosphorylated guanine derivative, ppGpp, and the role of ATP in initiation might be related to this synthesis . We discarded the role of ATP as being trivial and corresponding solely to the well-known effect on eukaryotic systems.

Med Biol, 1975 Oct, 53(5), 390 - 4
Translation of Semliki forest virus 42S and 26S RNAs in a cell-free system derived from Escherichia coli; Uomala P et al.; The SFV 42S RNA and the intracellular 26S RNA have been translated in a prokaryotic cell-free system, the E . coli S30 . About half of the {35S}methionine-labelled products directed by both RNAs had molecular weights larger than 20,000 on polyacrylamide gels . Both products contained tryptic peptides which comigrated with all the capsid and envelope protein-derived peptides . The most striking difference between the prokaryotic and eukaryotic systems lay in the translation of the 42 S RNA: The "42S RNA-specific nonstructural" peptides, which predominate in the eukaryotic systems, were apparently absent from the product translated by the prokaryotic system.

Biochim Biophys Acta, 1975 Oct 1, 407(2), 222 - 39
{Analysis of ribosomes by polyacrylamide gel electrophoresis (author's transl)}; Ledoigt G et al.; Ribosomal polymers, monomers and subunits from several eukaryotes and prokaryotes were isolated and analyzed by polyacrylamide gel electrophoresis . Extraction of RNA from ribosomal particles after their migration in a polyacrylamide gel, analyses by sedimentation in sucrose gradients and observations in the electron microscope were carried out in parallel . Attention was directed to the reproducibility, the precision and the limitations of the electrophoresis technique.

Nature, 1975 Sep 11, 257(5522), 106 - 10
Genetic perturbations that reveal tertiary conformation of tRNA precursor molecules; McClain WH et al.; The ubiquity of tRNA-like conformations in tRNA precursors of prokaryotes provides a common structural basis for precursor recognition by the maturation enzymes . This design eliminates need for multiple enzymes to achieve the maturation of different precursors . Moreover, the requirement of this specific conformation for maturation guards against the production of potentially deleterious mutant tRNAs.

J Biochem (Tokyo), 1975 Sep, 78(3), 637 - 9
Evolutionary information involved in primary structures of chloroplast-type ferredoxins; Wada K et al.; The complete amino acid sequence of a chloroplast-type ferredoxin from a fresh water prokaryote, Aphanothece sacrum, was determined . The sequence consisted of 96 amino acid residues and was homologous to those of ferredoxins of higher plants . Comparison of eight ferredoxins, including one from a green alga and three from blue-green algae, suggested that the sequences of algal ferredoxins were as different from one another as from those of higher plants . The relationship between the numbers of differences in amino acids and the period since separation from a common ancestor was not linear, even after correction for multiple substitution at an amino acid site in the sequence . It is very likely that the ferredoxins of angiosperms evolved rather rapidly and that those of algae, and particularly blue-green algae evolved rather slowly in the evolutionary scale . Several possible mechanisms of evolution of plants are discussed.

Biochem J, 1975 Sep, 149(3), 675 - 83
Prokaryote-eukaryote relationship and the amino acid sequence of plastocyanin from Anabaena variabilis; Aitken A; The amino acid sequence of plastocyanin from the prokaryotic blue-green alga Anabaena variabilis was determined . The protein consists of a single polypeptide chain of 105 residues . The amino acid sequence of the plastocyanin was compared with that of the eukaryotic green alga Chlorella fusca and with those of higher-plant plastocyanins . The considerable similarity between the prokaryotic and eukaryotic plastocyanins is discussed . Detailed evidence for the sequence of the protein has been deposited as Supplementary Publication SUP 50051 (13 pages) at the British Library (Lending Division), Boston Spa, Wetherby, W . Yorkshire LS23 7BQ, U.K., from whom copies may be obtained on the terms given in Biochem J . (1975) 145, 5.

Proc Natl Acad Sci U S A, 1975 Sep, 72(9), 3531 - 5
Gene transfer to human cells: transducing phage lambda plac gene expression in GMI-gangliosidosis fibroblasts; Horst J et al.; Genetic information from the bacterium Escherichia coli was transferred to human cells by means of the specialized transducing phage lambda plac carrying the bacterial z gene for the enzyme beta-galactosidase (geta-D-galactoside galactohydrolase, EC 3.2.1.23) . As recipient cells, cultured skin fibroblasts from a patient with generalized gangliosidosis (GMI-gangliosidosis Type I) characterized by a severe deficiency of beta-galactosidase activity were used . The deficient human cells were incubated with the bacteriophage lambda plac or lambda plac DNA and beta-galactosidase activity was measured in order to detect gene transfer and acceptance of the prokaryotic information in the mammalian system for transcription and translation . The expression of the phage genome in the deficient fibroblasts could be demonstrated by detection of higher beta-galactosidase activity after incubation with phage lambda plac in three out of 19 experiments and in four out of 16 experiments after treatment with lambda plac DNA . Lambda plac DNA induced much higher enzyme activities than infective phage particles . Immunochemical and physicochemical assays could not distinguish the induced beta-galactosidase activity from that of the z-gene product of E . coli.

J Mol Evol, 1975 Aug 5, 5(3), 167 - 76
The origin of mitochondria; Reijnders L; The endosymbiont and episome theories about the origin of mitochondria are reviewed . Biochemical and genetic data, relevant to these theories are discussed . An alternative theory is also proposed; this theory is that nuclear and mitochondrial DNAs developed from compartmentalized duplicate prokaryote DNAs.

Proc Natl Acad Sci U S A, 1975 Aug, 72(8), 3049 - 53
Site of aminoacylation of tRNAs from Escherichia coli with respect to the 2'- or 3'-hydroxyl group of the terminal adenosine; Sprinzl M et al.; A method is presented by which the site of primary attachment of the amino acids with respect to the 2'- or 3'-hydroxyl group of the terminal adenosine of E . coli tRNAs can be determined . It is found that the aminoacyl-tRNA synthetases (EC 6.1.1.-) with specificity for Arg, Asn, Ile, Leu, Met, Phe, Thr, Trp, and Val attach the amino acid to the 2'-position; those with specificity for Gly, His, Lys, and Ser attach the amino acid to the 3'-position; and that Tyr and Cys can be enzymatically attached to both the 2'- and 3'-positions . Together with previous experiments on yeast aminoacyl-tRNA synthetases, it is now shown that the specificity for one particular hydroxyl group is preserved during the evolution from prokaryotic to eukaryotic systems.

Proc Natl Acad Sci U S A, 1975 Aug, 72(8), 2900 - 4
Very stable prokaryotic messenger RNA in chromosomeless Escherichia coli minicells; Levy SB; E . coli minicells lack DNA, yet they make protein, the synthesis of which is sensitive to chloramphenicol but insensitive to rifamycin . This protein is coded for by very stable cellular mRNA with an estimated half-life of 40-80 min . In an R factor-containing minicell, two very different species of mRNA are observed: (i) R factor-specific mRNA with a short half-life whose synthesis is rifamycin-sensitive and (ii) cellular mRNA with a long half-life whose synthesis is rifamycin-insensitive . These findings indicate that minicells contain normal degradative mechanisms for mRNA and point out the existence of a unique class of very stable cellular mRNA . Greater than 80% of the rifamycin-insensitive protein synthesized goes into the outer minicell membrane . Relatively stable mRNA, half-life 5.5-11.5 min, for outer membrane protein in whole cells has been reported {Hirashima et al . (1973) J . Mol . Biol . 79, 373-389} . The stability of minicell mRNA is significantly greater . This and other observations suggest that there are two functional species of mRNA for outer membrane protein perhaps in different sites in the cell . Furthermore, these studies suggest that a class of cellular proteins is synthesized in bacteria without concomitant transcription and in the absence of association with chromosomal DNA.

J Bacteriol, 1975 Aug, 123(2), 704 - 16
Purification and properties of malate dehydrogenase from Pseudomonas testosteroni; You KS et al.; Nicotinamide adenine dinucleotide-linked malate dehydrogenase has been purified from Pseudomonas testosteroni (ATCC 11996) . The purification represents over 450-fold increase in specific activity . The amino acid composition of the enzyme was determined and found to be quite different from the composition of the malate dehydrogenases from animal sources as well as from Escherichia coli . Despite this difference, however, the data show that the enzymatic properties of the purified enzyme are remarkably similar to those of other malate dehydrogenases that have been previously studied . The Pseudomonas enzyme has a molecular weight of 74,000 and consists of two subunits of identical size . In addition to L-malate, the enzyme slowly oxidizes other four-carbon dicarboylates having an alpha-hydroxyl group of S configuration such as meso- and (-) tartrate . Rate-determining steps, which differ from that of the reaction involving L-malate, are discussed for the reaction involving these alternative substrates . Oxidation of hydroxymalonate, a process previously undetected with other malate dehydrogenases, is demonstrated fluorometrically . Hydroxymalonate and D-malate strongly enhance the fluorescence of the reduced nicotinamide adenine dinucleotide bound to the enzyme . The enzyme is A-stereospecific with respect to the coenzyme . Malate dehydrogenase is present in a single form in the Pseudomonas . The susceptibility of the enzyme to activation or inhibition by its substrates-particularly the favoring of the oxidation of malate at elevated concentrations-strongly resembles the properties of the mitochondrial enzymes . The present study reveals that whereas profound variations in chemical composition have occurred between the prokaryotic and eukaryotic enzymes, the physical and catalytic properties of malate dehydrogenase, unlike lactate dehydrogenase, are well conserved during the evolutionary process.

Biochim Biophys Acta, 1975 Jul 23, 395(4), 535 - 47
Histone-like protein in the prokaryote Thermoplasma acidophilum; Searcy DG; The DNA of the prokaryote Thermoplasma acidophilum is associated with a histone-like protein that has the following properties: it has a high content (23%) of basic amino acids, is positively charged at neutral pH, is soluble in acid, and can stabilize DNA against thermal denaturation . In polyacrylamide gel electrophoresis, in the presence of either sodium dodecylsulfate or urea, it migrates at the same rate as histone IV (F2a1) of calf thymus . The amino acid composition, however, it unusually rich in the amides of acidic amino acids (16-20%), and it does not appear to be closely homologous to any of the classes of eukaryotic histones . Escherichia coli DNA, on the other hand, was associated with no detectable acid-soluble proteins, and the nucleoprotein thermally denatured at a lower temperature than pure DNA.

Nucleic Acids Res, 1975 Jul, 2(7), 1177 - 88
The binding sites for tRNA on eukaryotic ribosomes; Leader DP et al.; We have studied the non-enzymic binding of phe-tRNA to ribosomes from rat liver using deacylated tRNA to inhibit binding to the P-site and puromycin (5 x 10-minus3M) to inhibit binding to the A-site . We conclude that at a low concentration of magnesium ions (10mM) phe-tRNA is bound only at the A-site of 80S irbosomes, whereas at a high concentration of magnesium ions (40mM) phe-tRNA is also bound at the P-site . Studies with edeine indicate that, during non-enzymic binding of phe-tRNA, eukaryotic ribosomes (in contrast to prokarotic ribosomes) have the A-site of the 60S subunit and the initiation site of the 40S subunit juxtaposed . This may account for the differences observed, in formation of diphenylalanyl-tRNA and phenylalanyl-puromycin, between phe-tRNA bound non-enzymically to the P-sites of eukaryotic and prokaryotic ribosomes.

Can J Microbiol, 1975 Jul, 21(7), 1058 - 80
Ultrastructure of the Alnus crispa var . mollis Fern . root nodule endophyte; Lalonde M et al.; Nitrogen-fixing, field-obtained root nodules of the silky green alder were studied by transmission electron microscopy . The nodule endophyte exhibited a prokaryotic cytology and was present in two forms: the hypha(0.3-1.0mum), which was branched and septate, and the vesicle (3-5mum), which was also septate and developed at the parental hypha tip . Bacteria-like cells, previously observed in light microscopy studies, were not seen in the present work . The actinomycete-like endophyte penetrated through the host cell wall and becane enveloped by a capsular material (0.1mum), the whole being enclosed by host membranes . In some host cells, the endophyte appeared to lyse and become a mass of shrunken debris . The fine structure of the Alnus crispa var . mollis root nodule endophyte was found to be similar to that of other nonleguminous root nodule endophytes.

J Bacteriol, 1975 Jul, 123(1), 336 - 45
Ultrastructal morphology of some prokaryotic microorganisms associated with the hindgut of cockroaches; Foglesong MA et al.; Scanning electron microscopy and transmission electron microscopy have been used to visualize the morphology and ultrastructure of two types of microorganisms in the hindgut of the cockroach Blaberus posticus . Both organisms, designated as either short or long rods, are attached to chitinous projections from the gut wall . Micrographs suggest that the organisms are prokaryotic with a cell wall complex characteristic of gram-negative bacteria . However, certain differences were noted between the cell wall complex of the two types . Two forms of the long-rod type were noted, with one form appearing to be a "degenerate" or "transitional" cell . In the degenerate cells, vesicles are observed that often are contiguous with the cytoplasmic membrane . There are indications that the long-rod type may divide by longitudinal fission . Neither the short- nor long-rod type has been cultivated in its respective recognizable form.

J Mol Evol, 1975 Jun 9, 5(1), 1 - 24
Phylogenies from amino acid sequences aligned with gaps: the problem of gap weighting; Fitch WM et al.; The common but generally overlooked problem of how best to construct phylogenies from orthologous amino acid sequences, when their alignment requires the placement therein of gaps denoting insertions/deletions in the evolutionary history of their genes since their common ancestor, has been studied . Three diverse methods were examined: 1 . each missing residue in a gap is weighted as equivalent to the average number of minimum nucleotide replacements in known conjugate amino acid pairs of those same two sequences, which weight necessarily differs for each pair of sequences; 2 . each missing residue in a gap is weighted as equivalent to a fixed number of nucleotide replacements; and 3 . each gap, regardless of length, is weighted as equivalent to a fixed number of nucleotide replacements . For the flavodoxins, each method yielded a different best tree and suggests that the choice of method may be crucial . For the plant ferredoxins, all methods give results inconsistent with botanical classification and suggests the sequences may not all be orthologous . For the bacterial ferredoxins, the method was less germane than the actual weight used, five different best trees being obtained depending upon the weight . The best tree for all ferredoxins (prokaryotic plus eukaryotic) combined proved to be greatly dependent upon the gap locations with several reasonable aligments yielding different best trees . They also suggest that functional equivalence may well prove to be a poor guide to which residues have a common ancestral codon . The rubredoxin sequences show that a partial internal gene duplication occurred in the Pseudomonas line, probably very soon after its divergence from the other genera . Together, the results clearly indicate that the phylogenetic answer one gets may greatly depend upon how one treats the gaps but they fail to indicate what treatment may be best.

Proc Natl Acad Sci U S A, 1975 Jun, 72(6), 2310 - 4
On the prokaryotic nature of red algal chloroplasts; Bonen L et al.; The sequences of oligonucleotides released by T1 ribonuclease digestion of 32-P-labeled 16S (chloroplast) and 18S (cytoplasmic) ribosomal RNAs from a marine species of Porphyridium (Rhodophyta) have been determined . The resultant catalogs have been compared to those obtained for three prokaryotes:Escherichia coli, Bacillus subtilis, and Anacystis nidulans (a blud-green alga) . There is extensive sequence homology between the Porphyridium chloroplast 16S ribosomal RNA and each of the prokaryotic 16S ribosomal RNAs, but little homology between the Porphyridium cytoplasmic 18S ribosomal RNA and any of the 16S species . These data provide a measure of the evolutionary distance separating existing chloroplasts from contemporary bacteria and blue-green algae, and are discussed in terms of the hypothesis that these organelles evolved from endosymbiotic photosynthetic prokaryotes.

Proc Natl Acad Sci U S A, 1975 Jun, 72(6), 2418 - 22
Phylogenetic origin of the chloroplast and prokaryotic nature of its ribosomal RNA; Zablen LB et al.; The 16S ribosomal RNA of the Euglena gracilis chloroplast has been characterized in terms of its two-dimensional electrophoretic "fingerprint" (T1 ribonuclease) . Results show it to be a typically prokaryotic 16 S rRNA . By the present criterion, different chloroplasts are shown to be related to one another and at least distantly to blue-green algae and perhaps to Bacillaceae . These results argue in favor of an endosymbiont origin of the chloroplast.

J Gen Virol, 1975 May, 27(2), 135 - 49
A classification of virus groups based on the size of the particle in relation to genome size; Matthews RE; For 59 different viruses, when the amount of nucleic acid in the particle is related either to the dry weight of the particle or to the particle volume, two classes of virus groups emerge--those with enveloped or those with geometrical particles . The enveloped viruses have particles with the following properties: (i) about 40 X 10-6 daltons of anhydrous weight per 10-6 daltons of nucleic acid; (ii) a particle volume of about 2 X 10-5 nm3 per 10-6 daltons of nucleic acid; (iii) a limiting lipoprotein membrane . These properties are qualitatively and quantitatively close to those of prokaryotic cells . The geometric viruses have particles with roughly one-tenth the anhydrous mass per unit of nucleic acid and one twenty-fifth the particle volume per unit of nucleic acid . They do not possess a limiting lipoprotein membrane.

J Bacteriol, 1975 May, 122(2), 719 - 26
Endogenous messenger ribonucleic acid-directed polypeptide chain elongation in a cell-free system from the yeast Saccharomyces cerevisiae; Gallis BM et al.; An in vitro protein-synthesizing system from the yeast Saccharomyces cerevisiae has been made by a modification of the procedure for preparation of the Krebs ascites system . The protein synthetic activity is directed by endogenous messenger . Amino acid incorporation occurs over a broad range of magnesium and potassium concentration, being maximal at 6 and 85 mM, respcetively . The activity of this in vitro system is due to the elongation of polypeptides whose synthesis was initiated in vivo . The cell extract does not initiate synthesis with endogenous messenger ribonucleic acid (RNA), since 1 muM pactamycin, which blocks initiation on prokaryotic or eukaryotic ribosomes invitro, fails to decrease amino acid incorporation . Ten micromolar cycloheximide, however, inhibits incorporation by 87% . Moreover, this system is not stimulated by rabbit reticulocyte polysomal RNA, which directs the synthesis of hemoglobin in extracts of Krebs ascites cells . The translation of this messenger is not masked by high endogenous incorporation, because autoradiography of sodium dodecyl sulfate-polyacrylamide gels containing {35-S}methionine-labeled products shows that no hemoglobin is made . Preincubation of this system, which reduces the high endogenous incorporation by 80%, does not increase its capacity to be stimulated by either rabbit reticulocyte RNA or yeast polyriboadenylic acid-containing RNA . Polyuridylic acid, however, does stimulate polyphenylalanine incorporation . The failure of the yeast lysate to be stimulated by or to translate added natural messenger RNA, its insensitivity to low levels of pactamycin but inhibition by cycloheximide, and its relatively high magnesium optimum (the same as that for polyuridylic acid) suggest that it elongates but does not initiate polypeptide chains.

J Biol Chem, 1975 Apr 25, 250(8), 3074 - 9
Comparison of fMet-tRNAf and Met-tRNAf from Escherichia coli and rabbit liver in initiation of hemoglobin synthesis; Elson NA et al.; A comparison has been made of the ability of the formylated and unformylated initiator tRNAs of Escherichia coli and rabbit liver to participate in a number of model reactions of protein synthesis . These reactions include: (a) formation of a ternary complex composed of the initiator tRNA, GTP, and initiation factor MP; (b) ApUpG-directed binding of the initiator tRNA to 40 S subunits with initiation factor Ml; (c) formation of the artificial dipeptide, methionylpuromycin; (d) formation of the natural initial globin dipeptide, methionylvaline; and (e) synthesis of sheep alpha and betaB-globin chains on reticulocyte polysomes from a type BB sheep . The results of these studies indicate that although the prokaryotic initiator tRNA species function efficiently in the partial reactions which involve only binding, the methionine donated by the prokaryotic tRNA is not incorporated efficiently into peptide linkage . This suggests that the initial high level of binding of the E . coli initiator tRNAs may be nonspecific, and that the structure of the tRNA itself is important for specific recognition by eukaryotic initiation factors . The effect of formylation on the effectiveness of the initiator tRNA is not clear; it reduces activity in ternary complex formation, does not affect ApUpG-directed binding to 40 S subunits, and increases the rate or extent of incorporation of methionine, or both, into methionylpuromycin and globin chains.

J Mol Evol, 1975 Mar 24, 4(4), 277 - 306
Deviations from compositional randomness in eukaryotic and prokaryotic proteins: the hypothesis of selective-stochastic stability and a principle of charge conservation; Holmquist R; Eight proteins of diverse lengths, functions, and origin, are examined for compositional non-randomness amino acid by amino acid . The proteins investigated are human fibrinopeptide A, guinea pig Insulin, rattlesnake cytochrome c, MS2 phage coat protein, rabbit triosephosphate isomerase, bovine pancreatic deoxyribonuclease A, bovine glutamate dehydrogenase, and Bacillus thermoproteolyticus thermolysin . As a result of this study the experimentally testable hypothesis is put forth that for a large class of proteins the ratio of that fraction of the molecule which exhibits compositional non-randomness to that fraction which does not is on the average, stable about a mean value (estimated as 0.32 plus or minus 0.17) and (nearly) independent of protein length . Stochastic and selective evolutionary forces are viewed as interacting rather than independent phenomena . With respect to amino acid composition, this coupling ameliorates the current controversy over Darwinian vs . non-Darwinian evolution, selectionist vs . neutralist, in favor of neither: Within the context of the quantitative data, the evolution of real proteins is seen as a compromise between the two viewpoints, both important . The compositional fluctuations of the electrically charged amino acids glutamic and aspartic acid, lysine and arginine, are examined in depth for over eighty protein families, both prokaryotic and eukaryotic . For both taxa, each of the acidic amino acids is present in amounts roughly twice that predicted from the genetic code . The presence of an excess of glutamic acid is independent of the presence of an excess of aspartic acid and vice versa.

Nature, 1975 Mar 6, 254(5495), 26 - 31
A gene cluster in Aspergillus nidulans with an internally located cis-acting regulatory region; Arst HN Jr et al.; Work reported here on the fungus Aspergillus nidulans has provided the first definitive demonstration of operon-type organisation in an eukaryote genome . It has been shown that the prnA and prnB genes concerned with proline metabolism form a gene cluster with the regulatory region lying between the two putative structural genes prnA and prnB . Regulatory mutations (prnd) probably leading to relief of carbon catabolite repression, map in between prnA and prnB and are cis-dominant with respect to both . The properties of these regulatory mutations and other findings suggest that carbon catabolite repression may be mediated by a negative control system in A . nidulans . This gene cluster is particularly interesting in view of its divergent orientation (with the regulatory region located in the centre of the operon) and for the fact that unlike the divergent operons known in prokaryotes, the divergent orientation is related to the way in which this particular operon may be regulated.

Can J Biochem, 1975 Mar, 53(3), 320 - 7
Wheat-embryo ribonucleates . IV . Factors that influence the formation and stability of a complex between 5S rRNA and 18S rRNA; Azad AA et al.; Under the conditions used in this study, wheat-embryo 5S rRNA complexes with its homologous 18S rRNA from wheat embryos and with heterologous 18S rRNA from other eukaryotic source materials such as yeast, L cells, and HeLa cells, but it does not complex with heterologous 16S rRNA from a prokaryote such as Escherichia coli or with homologous or heterologous 26S (23S) rRNA of either eukaryotic or prokaryotic origin . If a solution of wheat-embryo rRNA is simply made 0.3 M with respect to NaCl and then heated at 60 degress C for 3 min before quick cooling to room temperature (ca . 20 degrees C), there is both preferential and efficient complex formation between 5S and 18S rRNA . The 'laboratory-prepared' complex between wheat-embryo 5S rRNA and its homologous 18S rRNA is more thermostable in 0.1 M NaCl solution than is the 'natural' complexes 'melt' over a narrow range of temperature . The possible physicochemical and physiological importance of both homologous and heterologous rRNA complexes is the subject of a brief discussion.

Appl Microbiol, 1975 Mar, 29(3), 352 - 7
Effect of relative humidity on the survival of airborne unicellular algae; Ehresmann DW et al.; A method is described which is suitable for assessing the effects of relative humidity (RH) on the viability of two unicellular algae in experimental aerosols . Viable cells of Nannochloris atomus collected from the airborne state were detected by plating onto agar surfaces of an appropriate growth medium, whereas viable airborne cells of Synechococcus sp., because of unreliable growth on solid media, were determined by a liquid assay system . The assays were performed at intervals during short-term and prolonged storage of algal aerosols in chambers preconditioned to a selected RH and temperature . Both species showed the greatest loss in viability during the first minute after atomization, and the extent of this inactivation, as a function of RH, reflected the subsequent long-term survival . The airborne eukaryotic alga was unable to survive at an RH below 91%, whereas the airborne prokaryotic alga was comparatively stable over a wide humidity range . Initial inactivation was least and long-term survival best, for both species, at 94% RH.

Proc Natl Acad Sci U S A, 1975 Mar, 72(3), 859 - 63
RNA-directed DNA synthesis by the DNA polymerase of Rous sarcoma virus: structural and functional identification of 4S primer RNA in uninfected cells; Faras AJ et al.; The RNA-directed DNA polymerase of Rous sarcoma virus requires a 4S RNA molecule as primer for the initiation of DNA synthesis on the viral 70S RNA genome . We have now functionally identified primer activity in uninfected cells on the basis of the capacity of cellular 4S RNA to actively participate in the initiation of DNA synthesis by the RNA-directed DNA polymerase of Rous sarcoma virus in vitro . This was accomplished by reconstitution experiments in which 4S RNA from uninfected avian cells was tested for its ability to restore template activity to the viral RNA genome from which all primer had been removed . Similar reconstitution experiments were employed to demonstrate a primer activity in the 4S RNA population of duck, mouse, and human cells . Primer activity appears to be absent in lower eukaryotic or prokaryotic cells . Unambiguous identification of the Rous sarcoma virus primer molecule in uninfected cells was accomplished by directly purifying a 4S RNA molecule from the bulk of host cell transfer RNA and establishing structural similarities between this cellular 4S RNA species and the Rous sarcoma virus primer by two-dimensional paper electrophoresis of oligonucleotides obtained from a T1 ribonuclease digest of the RNA species . We conclude that the Rous sarcoma virus DNA polymerase can utilize a host cell molecule as primer for the initiation of RNA-directed DNA synthesis in vitro.

Proc Natl Acad Sci U S A, 1975 Feb, 72(2), 553 - 7
Genetic evidence on the organization and action of the qa-1 gene product: a protein regulating the induction of three enzymes in quinate catabolism in Neurospora crassa; Case ME et al.; The first three reactions in the catabolism of qainic acid in Neurospora crassa are under the genetic control of the qa gene cluster . This cluster consists of three structural genes encoding three inducible enzymes plus a regulatory gene (qa-1+) whose diffusible product apparently acts in a positive fashion to initiate coordinate synthesis of the three enzymes when an appropriate inducer is present . Genetic and biochemical evidence for both complementing and temperature-sensitive qa-1 alleles indicates that the product of the qa-1+ gene is an oligomeric (multimeric) protein . On the basis of cis-trans tests of appropriate double mutants (plus genetic mapping data for temperature-sensitive mutants), at least certain constitutive mutants (which produce all three qa enzymes in the absence of an inducer) are mutants in the regulatory gene and not in controlling elements such as initiators . The detection of stable (non-revertible) qa-1 intralocus deletion (multisite)mutants provides additional evidence for positive regulation in the qa system . Extensive genetic recombination data provide evidence that the two types of qa-1 mutants--slow-complementing (qa-1-s) and fast-complementing (qa-1-f)--map in discrete, non-overlapping segments of the qa-1 locus . These two distinct types of mutants are hypothesized to produce altered regulatory protein molecules that fail to interact either with a DNA initiator site (qa-1-s types) or with an inducer (qa-1-f types) . The striking similarities between the qa system in this lower eukaryote and certain prokaryote operon systems are discussed.

Bibl Haematol, 1975, (40), 405 - 8
Nonviral helper factors for leukemia virus expression in mice; Steeves RA; Nonviral helper factors as well as murine leukemia viruses (MuLV) can increase the infectivity of Friend spleen focus-forming virus (SFFV) in mice which restrict its natural helper virus . Such factors have been isolated from cell-free extracts of human leukemic spleens, bacteria, and mycoplasmata . Unlike immunodepressants and target cell stimulators (which can also increase the pathogenicity of SFFV if applied before infection), nonviral helper factors are most efficient when they are injected with SFFV into helper virus-restrictive mice . In these respects the nonviral factors resemble MuLV . However, helper factors differ from MuLV by their inability to replicate in neonatal mice and by their greater stability to heat . Although the human leukemic helper (HuLV) extracts examined lack detectable mycoplasma or bacterial contamination, the helper assay in mice will be of limited value as a possible detection system for human leukemogenic viruses until a unique marker is found by which to distinguish HuLH activity from that of prokaryotic origin . This makes a systematic comparison among the nonviral helper factors all the more important.

Adv Biophys, 1975, 7, 91 - 162
DNA repair and evolutionary considerations . A search for a general principle in nuclear biology with use of radiation as a probe; Kondo S; Three types of DNA repair are known: photoenzymatic repair, excision repair, and tolerance repair (the ability to generate damage-free copies of DNA, which could be not exact copies, from damaged DNA templates) . Photoenzymatic repair involves the most simple molecular mechanisms and is the most specific (effective only for pyrimidine dimers) and the most widely distributed among present living organisms, followed by excision repair and then by tolerance repair in order of increasing complexity . It is proposed that these repair systems also evolved in this order after the primordial life was created by solar UV light . Current but fragmentary evidence concerning the molecular and genetic bases of the three types of repair tends to support the idea that the increase in DNA-content needed for the evolution of higher forms from the prokaryotes may have been accompanied by the inherent threat of fragility of the giant DNA molecules, so that the higher forms now possess a greatly increased tolerance capacity . Probably the increase is approximately proportional to their DNA content compared with that of prokaryotes . It is shown theoretically that photoenzymatic and excision repair alone cannot deal with the inherent fragility of giant DNA . The development of tolerance-repair capacity, however, inevitably enhances probability of errors in the repair of DNA damage, leading to the accumulation of misrepair events such as mutation, chromosomal aberration and cancer . It is proposed that DNA repair and misreplication repair are responsible for preventing living organisms from regressing to the randomness-dominated world of the non-living . Living organisms would have evolved slowly along zigzag lines between error and repair of DNA.

Nucleic Acids Res, 1975 Jan, 2(1), 61 - 78
Formylatable methionine transfer RNA from Mycoplasma: purification and comparison of partial nucleotide sequences with those of other prokaryotic initiator tRNAs; Walker RT et al.; The major species of the formylatable methionine tRNA from Mycoplasma mycoides var capri has been purified . The 5'- and 3'-terminal sequences of the purified tRNA are pC-G- and C-A-A-C-C-AOH, respectively . Thus, this tRNA also contains the unique structural feature found in two other prokaryotic initiator tRNAs in that the first nucleotide at the 5'-end cannot form a Watson-Crick type of base-pair to the fifth nucleotide from the 3'-end . The Mycoplasma tRNA does not contain ribothymidine; however, a specific uridine residue in the sequence G-U-psi-C-G- can be enzymatically methylated by E . coli extracts to yield G-T-psi-C-G . Since ribothymidine is absent in crude tRNA from this strain of Mycoplasma, the absence of T is probably due to the lack of a U yields T modifying enzyme.

Z Allg Mikrobiol, 1975, 15(4), 259 - 68
{Effect of several plant growth regulators on various prokaryotes and their viruses}; Menzel G et al.; 26 plant growth regulators including herbicides were investigated in their effect on the multiplication of Escherichia coli, Bacillus subtilis, and the blue-green alga Plectonema boryanum as well as the RNA phages M 12 and Qbeta and the DNA phages lambda, phi 105, and LPP-1 employing the agar diffusion method . Nearly all of the compounds inhibited and/or stimulated one or some of the prokaryotes tested . The most frequent and strongest effects occurred in Pl . boryanum, the least effects in E . coli . The multiplication of phages was also influenced by plant growth regulators leading to increase, decrease or non-appearance of plaques . The investigations with the temperate phages lambda and phi 105 suggested part of the compounds to be able to interfere with the process of lysogenization . The results are discussed comparatively involving correspondent findings referred to in literature.

Ciba Found Symp, 1975, (31), 3 - 22
The roots of bioenergetics; Lipmann F; Publication Types:

Historical Article

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